media: cxd2841er: ensure that status will always be available

The loop with read status use a dynamic timeout value, calculated
from symbol rate. It should run the loop at least one time for
the status to be handled after the loop.

While this should, in practice, happen every time, it doesn't
hurt to change the logic to make it explicit.

This solves a smatch warning:
	drivers/media/dvb-frontends/cxd2841er.c:3350 cxd2841er_set_frontend_s() error: uninitialized symbol 'status'.

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>