purism: librem5: Fix a function declaration in spl.c

Here we implement usb_gadget_handle_interrupts() but did not include
<linux/usb/gadget.h> so did not have the declaration correct. Fix this
and add the missing include.

Signed-off-by: Tom Rini <trini@konsulko.com>
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Cc: Angus Ainslie <angus@akkea.ca>
Cc: kernel@puri.sm
1 file changed