[media] drxk: better handle errors

As reported by smatch:
	drivers/media/dvb-frontends/drxk_hard.c:3277 dvbt_sc_command() warn: missing break? reassigning 'status'

This is basically because the error handling logic there was crappy.

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