USB: gadget: udc: fix const issue in gadget_match_driver()

gadget_match_driver() takes a const pointer, and then decides to cast it
away into a non-const one, which is not a good thing to do overall.  Fix
this up by properly setting the pointers to be const to preserve that
attribute.

Fixes: d69d8048 ("driver core: have match() callback in struct bus_type take a const *")
Link: https://lore.kernel.org/r/2025052139-rash-unsaddle-7c5e@gregkh


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>