usb: gadget: net2272: Use irqflags in the call to net2272_probe_fin

Currently the variable irqflags is being set but is not being used,
it appears it should be used in the call to net2272_probe_fin
rather than IRQF_TRIGGER_LOW being used. Kudos to Uwe Kleine-König
for suggesting the fix.

Cleans up clang scan build warning:
drivers/usb/gadget/udc/net2272.c:2610:15: warning: variable 'irqflags'
set but not used [-Wunused-but-set-variable]

Fixes: ceb80363

 ("USB: net2272: driver for PLX NET2272 USB device controller")
Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Link: https://lore.kernel.org/r/20240307181734.2034407-1-colin.i.king@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>