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/pico-pi-imx6ul_defconfig b/configs/pico-pi-imx6ul_defconfig
index 3adccbb..9049a49 100644
--- a/configs/pico-pi-imx6ul_defconfig
+++ b/configs/pico-pi-imx6ul_defconfig
@@ -18,7 +18,7 @@
 CONFIG_BOARD_EARLY_INIT_F=y
 CONFIG_SPL_I2C_SUPPORT=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_CMD_BOOTMENU=y
 CONFIG_CMD_MEMTEST=y