[media] xc4000: Update firmware name

The firmware name at:
   http://www.kernellabs.com/firmware/xc4000/

Is different from the one at the Kernel. Update it
try first the new name, falling back to the previous one
if the new name can't be found.

Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>