drivers: 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/drivers/gpio/Makefile b/drivers/gpio/Makefile
index da0faf0..990a670 100644
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -3,7 +3,7 @@
 # Copyright 2000-2008
 # Wolfgang Denk, DENX Software Engineering, wd@denx.de.
 
-ifndef CONFIG_SPL_BUILD
+ifndef CONFIG_XPL_BUILD
 obj-$(CONFIG_DWAPB_GPIO)	+= dwapb_gpio.o
 obj-$(CONFIG_AXP_GPIO)		+= axp_gpio.o
 obj-$(CONFIG_DM_74X164)		+= 74x164_gpio.o