[media] dib0090: Remove a dead code

As reported by smatch:
	drivers/media/dvb-frontends/dib0090.c:1710 dib0090_dc_offset_calibration() warn: missing break? reassigning '*tune_state'

There's no need to change tune_state there, as the fall though code
will change it again to another state. So, simplify it by
removing the dead code.

While here, fix a typo:
	Sart => Start

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