[media] lirc_igorplugusb: Fix a compilation waring

drivers/staging/lirc/lirc_igorplugusb.c: In function ‘usb_remote_probe’:
drivers/staging/lirc/lirc_igorplugusb.c:393: warning: format ‘%lu’ expects type ‘long unsigned int’, but argument 3 has type ‘unsigned int’

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>