Rename GPIO_SUPPORT to GPIO

Rename these options so that CONFIG_IS_ENABLED can be used with them.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/configs/mccmon6_sd_defconfig b/configs/mccmon6_sd_defconfig
index a2d3e44..5c1aea8 100644
--- a/configs/mccmon6_sd_defconfig
+++ b/configs/mccmon6_sd_defconfig
@@ -1,7 +1,7 @@
 CONFIG_ARM=y
 CONFIG_ARCH_MX6=y
 CONFIG_SYS_TEXT_BASE=0x17800000
-CONFIG_SPL_GPIO_SUPPORT=y
+CONFIG_SPL_GPIO=y
 CONFIG_SPL_LIBGENERIC_SUPPORT=y
 CONFIG_NR_DRAM_BANKS=1
 CONFIG_ENV_SIZE=0x20000