[media] stv090x: Remove an unreachable code

if STV090x_RANGEOK is not returned, then STV090x_OUTOFRANGE
is returned. However, that part of the code is never reached,
as pointed by smatch:

	drivers/media/dvb-frontends/stv090x.c:2673 stv090x_get_sig_params() info: ignoring unreachable code.

So, remove the two uneeded elses, with makes the code a little bit
cleaner.

No functional changes, and one less smatch warning.

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