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/pico-imx7d_bl33_defconfig b/configs/pico-imx7d_bl33_defconfig
index 9fda669..5818dd8 100644
--- a/configs/pico-imx7d_bl33_defconfig
+++ b/configs/pico-imx7d_bl33_defconfig
@@ -1,6 +1,6 @@
 CONFIG_ARM=y
 CONFIG_ARCH_MX7=y
-CONFIG_SPL_GPIO_SUPPORT=y
+CONFIG_SPL_GPIO=y
 CONFIG_SPL_LIBCOMMON_SUPPORT=y
 CONFIG_SPL_LIBGENERIC_SUPPORT=y
 CONFIG_SYS_MEMTEST_START=0x80000000