V4L/DVB (11226): avoid warnings for request_ihex_firmware on dabusb and vicam

drivers/media/video/usbvideo/vicam.c: In function ‘vicam_open’:
drivers/media/video/usbvideo/vicam.c:194: warning: ‘fw’ may be used uninitialized in this function
drivers/media/video/dabusb.c: In function ‘dabusb_probe’:
drivers/media/video/dabusb.c:337: warning: ‘fw’ may be used uninitialized in this function

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