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>

drivers/media/i2c/ov9650.c

@@ -886,10 +886,12 @@ static int __g_volatile_ctrl(struct ov965x *ov965x, struct v4l2_ctrl *ctrl)
 		if (ctrl->val == V4L2_EXPOSURE_MANUAL)
 			return 0;
 		ret = ov965x_read(client, REG_COM1, &reg0);
-		if (!ret)
+		if (ret < 0)
-			ret = ov965x_read(client, REG_AECH, &reg1);
+			return ret;
-		if (!ret)
+		ret = ov965x_read(client, REG_AECH, &reg1);
-			ret = ov965x_read(client, REG_AECHM, &reg2);
+		if (ret < 0)
+			return ret;
+		ret = ov965x_read(client, REG_AECHM, &reg2);
 		if (ret < 0)
 			return ret;
 		exposure = ((reg2 & 0x3f) << 10) | (reg1 << 2) |