Rework xc_write_reg function for correct read register of the xc5000.
It is very useful for tm6000.

Tested for tm6000 and for saa7134 works well.
Signed-off-by: NBeholder Intl. Ltd. Dmitry Belimov <d.belimov@gmail.com>
Acked-by: NDevin Heitmueller <dheitmueller@kernellabs.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>