[media] siano: remove the bogus firmware lookup code

There is an special lookup code that is called when
SMS_BOARD_UNKNOWN. The logic there is bogus and will cause
an oops, as .type is SMS_UNKNOWN_TYPE (-1).
As the code would do:
	return smscore_fw_lkup[type][mode];
That would mean that it would try to go past the
smscore_fw_lkup table.
So, just remove that bogus code, simplifying the logic.

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