global: Rename SPL_ to XPL_

Use XPL_ as the symbol to indicate an SPL build. This means that SPL_ is
no-longer set.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/board/bosch/guardian/Makefile b/board/bosch/guardian/Makefile
index 20cecbf..8e38881 100644
--- a/board/bosch/guardian/Makefile
+++ b/board/bosch/guardian/Makefile
@@ -5,7 +5,7 @@
 # Copyright (C) 2018 Robert Bosch Power Tools GmbH
 #
 
-ifeq ($(CONFIG_$(SPL_)SKIP_LOWLEVEL_INIT),)
+ifeq ($(CONFIG_$(XPL_)SKIP_LOWLEVEL_INIT),)
 obj-y	:= mux.o
 endif
 
diff --git a/board/freescale/common/Makefile b/board/freescale/common/Makefile
index c491dc8..c2c86c0 100644
--- a/board/freescale/common/Makefile
+++ b/board/freescale/common/Makefile
@@ -34,7 +34,7 @@
 endif
 obj-$(I2C_COMMON)		+= i2c_common.o
 obj-$(CONFIG_FSL_USE_PCA9547_MUX)		+= i2c_mux.o
-obj-$(CONFIG_$(SPL_)VID)	+= vid.o
+obj-$(CONFIG_$(XPL_)VID)	+= vid.o
 obj-$(CONFIG_FSL_QIXIS)	+= qixis.o
 ifndef CONFIG_XPL_BUILD
 obj-$(CONFIG_ID_EEPROM)	+= sys_eeprom.o
@@ -54,7 +54,7 @@
 obj-$(CONFIG_TARGET_P3041DS)		+= ics307_clk.o
 obj-$(CONFIG_TARGET_P4080DS)		+= ics307_clk.o
 obj-$(CONFIG_TARGET_P5040DS)		+= ics307_clk.o
-ifeq ($(CONFIG_$(SPL_)POWER_LEGACY),y)
+ifeq ($(CONFIG_$(XPL_)POWER_LEGACY),y)
 obj-$(CONFIG_POWER_PFUZE100)	+= pfuze.o
 endif
 obj-$(CONFIG_DM_PMIC_PFUZE100)	+= pfuze.o
diff --git a/board/st/common/Makefile b/board/st/common/Makefile
index b01245e..fda48d2 100644
--- a/board/st/common/Makefile
+++ b/board/st/common/Makefile
@@ -8,7 +8,7 @@
 
 ifeq ($(CONFIG_ARCH_STM32MP),y)
 obj-$(CONFIG_SET_DFU_ALT_INFO) += stm32mp_dfu.o
-obj-$(CONFIG_$(SPL_)DFU_VIRT) += stm32mp_dfu_virt.o
+obj-$(CONFIG_$(XPL_)DFU_VIRT) += stm32mp_dfu_virt.o
 endif
 
 obj-$(CONFIG_TYPEC_STUSB160X) += stusb160x.o
diff --git a/board/tcl/sl50/Makefile b/board/tcl/sl50/Makefile
index 0ac0ba3..1502990 100644
--- a/board/tcl/sl50/Makefile
+++ b/board/tcl/sl50/Makefile
@@ -4,7 +4,7 @@
 #
 # Copyright (C) 2015 Toby Churchill Ltd - http://www.toby-churchill.com/
 
-ifeq ($(CONFIG_$(SPL_)SKIP_LOWLEVEL_INIT),)
+ifeq ($(CONFIG_$(XPL_)SKIP_LOWLEVEL_INIT),)
 obj-y	:= mux.o
 endif
 
diff --git a/board/ti/am335x/Makefile b/board/ti/am335x/Makefile
index 2b1e21a..6ef87c2 100644
--- a/board/ti/am335x/Makefile
+++ b/board/ti/am335x/Makefile
@@ -4,7 +4,7 @@
 #
 # Copyright (C) 2011 Texas Instruments Incorporated - https://www.ti.com/
 
-ifeq ($(CONFIG_$(SPL_)SKIP_LOWLEVEL_INIT),)
+ifeq ($(CONFIG_$(XPL_)SKIP_LOWLEVEL_INIT),)
 obj-y	:= mux.o
 endif
 
diff --git a/board/ti/am43xx/Makefile b/board/ti/am43xx/Makefile
index b618f63..5b7b5b3 100644
--- a/board/ti/am43xx/Makefile
+++ b/board/ti/am43xx/Makefile
@@ -4,7 +4,7 @@
 #
 # Copyright (C) 2013 Texas Instruments Incorporated - https://www.ti.com/
 
-ifeq ($(CONFIG_$(SPL_)SKIP_LOWLEVEL_INIT),)
+ifeq ($(CONFIG_$(XPL_)SKIP_LOWLEVEL_INIT),)
 obj-y	:= mux.o
 endif
 
diff --git a/board/vscom/baltos/Makefile b/board/vscom/baltos/Makefile
index 2b1e21a..6ef87c2 100644
--- a/board/vscom/baltos/Makefile
+++ b/board/vscom/baltos/Makefile
@@ -4,7 +4,7 @@
 #
 # Copyright (C) 2011 Texas Instruments Incorporated - https://www.ti.com/
 
-ifeq ($(CONFIG_$(SPL_)SKIP_LOWLEVEL_INIT),)
+ifeq ($(CONFIG_$(XPL_)SKIP_LOWLEVEL_INIT),)
 obj-y	:= mux.o
 endif
 
diff --git a/board/xilinx/zynqmp/Makefile b/board/xilinx/zynqmp/Makefile
index 544346d..6476f20 100644
--- a/board/xilinx/zynqmp/Makefile
+++ b/board/xilinx/zynqmp/Makefile
@@ -31,7 +31,7 @@
 endif
 endif
 
-obj-$(CONFIG_$(SPL_)ZYNQMP_PSU_INIT_ENABLED) += $(init-objs)
+obj-$(CONFIG_$(XPL_)ZYNQMP_PSU_INIT_ENABLED) += $(init-objs)
 
 ifdef CONFIG_XPL_BUILD
 ifneq ($(CONFIG_ZYNQMP_SPL_PM_CFG_OBJ_FILE),"")