media: ov9650: fix bogus warnings

The smatch logic gets confused with the syntax used to check if the
ov9650x_read() reads succedded:
	drivers/media/i2c/ov9650.c:895 __g_volatile_ctrl() error: uninitialized symbol 'reg2'.
	drivers/media/i2c/ov9650.c:895 __g_volatile_ctrl() error: uninitialized symbol 'reg1'.

There's nothing wrong with the original logic, except that
it is a little more harder to review.

So, let's stick with the syntax that won't cause read
issues.

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Reviewed-by: Nicholas Mc Guire <hofrat@osadl.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>