configs: meson: enable missing DM_USB_GADGET

Since commit b96640cbfb ("ARM: meson: g12a: switch dwc2 otg to DM")
and commit e327e2affd ("ARM: meson: switch AXG & GX dwc2 otg to DM")
Amlogic boards now requires DM_USB_GADGET to have USB Gadget to work.

Add it to the boards configs as returned by:
$ grep -L DM_USB_GADGET $(grep -l CONFIG_USB_GADGET $(grep -l MESON configs/*))

Fixes: b96640cbfb ("ARM: meson: g12a: switch dwc2 otg to DM")
Fixes: e327e2affd ("ARM: meson: switch AXG & GX dwc2 otg to DM")
Link: https://lore.kernel.org/r/20231206-u-boot-m2s-fix-usb-gadget-v1-1-1c4c66cd10f3@linaro.org
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
diff --git a/configs/radxa-zero2_defconfig b/configs/radxa-zero2_defconfig
index e941576..b795681 100644
--- a/configs/radxa-zero2_defconfig
+++ b/configs/radxa-zero2_defconfig
@@ -52,6 +52,7 @@
 CONFIG_DEBUG_UART_SKIP_INIT=y
 CONFIG_MESON_SERIAL=y
 CONFIG_USB=y
+CONFIG_DM_USB_GADGET=y
 CONFIG_USB_XHCI_HCD=y
 CONFIG_USB_XHCI_DWC3=y
 CONFIG_USB_DWC3=y