board: Use CONFIG_XPL_BUILD instead of CONFIG_SPL_BUILD

Use the new symbol to refer to any 'SPL' build, including TPL and VPL

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/board/engicam/common/Makefile b/board/engicam/common/Makefile
index 15f0eaa..dc8be38 100644
--- a/board/engicam/common/Makefile
+++ b/board/engicam/common/Makefile
@@ -1,7 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0+
 # Copyright (C) 2016 Amarula Solutions B.V.
 
-ifdef CONFIG_SPL_BUILD
+ifdef CONFIG_XPL_BUILD
 obj-$(CONFIG_IMX6_ENGICAM_COMMON) += spl.o
 else
 obj-$(CONFIG_IMX6_ENGICAM_COMMON) += board.o
diff --git a/board/engicam/imx8mm/Makefile b/board/engicam/imx8mm/Makefile
index 3392d61..d6ad299 100644
--- a/board/engicam/imx8mm/Makefile
+++ b/board/engicam/imx8mm/Makefile
@@ -6,7 +6,7 @@
 
 obj-y += icore_mx8mm.o
 
-ifdef CONFIG_SPL_BUILD
+ifdef CONFIG_XPL_BUILD
 obj-y += spl.o
 obj-y += lpddr4_timing.o
 endif
diff --git a/board/engicam/imx8mp/Makefile b/board/engicam/imx8mp/Makefile
index c3ec09d..f21a31b 100644
--- a/board/engicam/imx8mp/Makefile
+++ b/board/engicam/imx8mp/Makefile
@@ -6,7 +6,7 @@
 
 obj-y += icore_mx8mp.o
 
-ifdef CONFIG_SPL_BUILD
+ifdef CONFIG_XPL_BUILD
 obj-y += spl.o
 obj-$(CONFIG_IMX8M_LPDDR4) += lpddr4_timing.o
 endif
diff --git a/board/engicam/stm32mp1/Makefile b/board/engicam/stm32mp1/Makefile
index 155d33f..9ac78e4 100644
--- a/board/engicam/stm32mp1/Makefile
+++ b/board/engicam/stm32mp1/Makefile
@@ -3,7 +3,7 @@
 # Copyright (C) 2018, STMicroelectronics - All Rights Reserved
 #
 
-ifdef CONFIG_SPL_BUILD
+ifdef CONFIG_XPL_BUILD
 obj-y += spl.o
 else
 obj-y += stm32mp1.o