[media] lbdt3306a: simplify the lock status check

[media] lbdt3306a: simplify the lock status check

The logic there is too complex and it looks like an inifite
loop.

So, simplify the logic and implement it as a for loop.

This gets rid of the following checkpatch.pl warnings:

WARNING: else is not generally useful after a break or return
+			return LG3306_UNLOCK;
+		} else {

WARNING: else is not generally useful after a break or return
+			return LG3306_UNLOCK;
+		} else {

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