[media] em28xx: MaxMedia UB425-TC change demod settings

That version of DRX-K chip supports only 2.
drxk: SCU_RESULT_INVPAR while sending cmd 0x0203 with params:
drxk: Warning -22 on qam_demodulator_command

Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>