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/drivers/Makefile b/drivers/Makefile
index b06a61e..0ce9c82 100644
--- a/drivers/Makefile
+++ b/drivers/Makefile
@@ -5,7 +5,7 @@
 obj-$(CONFIG_$(SPL_TPL_)CLK) += clk/
 obj-$(CONFIG_$(SPL_TPL_)DM) += core/
 obj-$(CONFIG_$(SPL_TPL_)DFU) += dfu/
-obj-$(CONFIG_$(SPL_TPL_)GPIO_SUPPORT) += gpio/
+obj-$(CONFIG_$(SPL_TPL_)GPIO) += gpio/
 obj-$(CONFIG_$(SPL_TPL_)DRIVERS_MISC_SUPPORT) += misc/
 obj-$(CONFIG_$(SPL_TPL_)SYSRESET) += sysreset/
 obj-$(CONFIG_$(SPL_TPL_)FIRMWARE) +=firmware/