[media] xc4000: remove xc5000 firmware loading routine

Since we use the xc3028 version of the firmware file parsing routine (which
includes support for scodes and separate blobs), we can drop the xc5000
version of the code.

Signed-off-by: Devin Heitmueller <dheitmueller@kernellabs.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>