mn88472: fix chip id check on probe

mn88472: fix chip id check on probe

commit 365fe4e0ce218dc5ad10df17b150a366b6015499 upstream.

A register used to identify chip during probe was overwritten during
firmware download and due to that later probe's for warm chip were
failing. Detect chip from the another register, which is located on
different register bank 2.

Fixes: 94d0eaa41987 ("[media] mn88472: move out of staging to media")
Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>