usb: gadget: avoid unusual inline assembly

clang does not understand the "mrc%?" syntax:

drivers/usb/gadget/udc/pxa25x_udc.c:2330:11: error: invalid % escape in inline assembly string

I don't understand it either, but removing the %? here gets it to build.
This is probably wrong and someone else should do a proper patch.

Any suggestions?

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20210927123830.1278953-1-arnd@kernel.org


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