Kconfig: rename CONFIG_SPL_USB_GADGET_SUPPORT as CONFIG_SPL_USB_GADGET

The SPL option for USB gadget should be named after the option for u-boot
(CONFIG_USB_GADGET)

Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>
diff --git a/common/spl/Kconfig b/common/spl/Kconfig
index 35472f4..37ecbc6 100644
--- a/common/spl/Kconfig
+++ b/common/spl/Kconfig
@@ -776,13 +776,13 @@
 	  config options. This enables loading from USB using a configured
 	  device.
 
-config SPL_USB_GADGET_SUPPORT
+config SPL_USB_GADGET
 	bool "Suppport USB Gadget drivers"
 	help
 	  Enable USB Gadget API which allows to enable USB device functions
 	  in SPL.
 
-if SPL_USB_GADGET_SUPPORT
+if SPL_USB_GADGET
 
 config SPL_USB_ETHER
 	bool "Support USB Ethernet drivers"