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/configs/display5_factory_defconfig b/configs/display5_factory_defconfig
index 6ef85e2..4c73a3a 100644
--- a/configs/display5_factory_defconfig
+++ b/configs/display5_factory_defconfig
@@ -25,7 +25,7 @@
 CONFIG_SPL_OS_BOOT=y
 CONFIG_SPL_SPI_LOAD=y
 CONFIG_SPL_USB_HOST_SUPPORT=y
-CONFIG_SPL_USB_GADGET_SUPPORT=y
+CONFIG_SPL_USB_GADGET=y
 CONFIG_SPL_USB_SDP_SUPPORT=y
 CONFIG_SPL_WATCHDOG_SUPPORT=y
 CONFIG_HUSH_PARSER=y