usb: gadget: Mark dm_usb_gadget_handle_interrupts as non-weak for DM_USB_GADGET

usb: gadget: Mark dm_usb_gadget_handle_interrupts as non-weak for DM_USB_GADGET

The dm_usb_gadget_handle_interrupts() is not implemented by any USB
gadget controller drivers which do enable DM_USB_GADGET anymore. Set
the symbol as non-weak.

Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
Reviewed-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>
Tested-by: Alexander Sverdlin <alexander.sverdlin@siemens.com>
Tested-by: Mattijs Korpershoek <mkorpershoek@baylibre.com> # vim3
Link: https://lore.kernel.org/r/20240614005309.34433-12-marek.vasut+renesas@mailbox.org
Signed-off-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>