media:i2c: fix kernel warning

media:i2c: fix kernel warning

ov10823 http://git-master/r/#/c/1301746/
ov9281 http://git-master/r/#/c/1301718/
imx185  http://git-master/r/#/c/1301799/
Add fix for pca9570
Enable -Werror in makefile

Change-Id: Id77c9a559feb26ec235939236a0282b6ccbe60a1
Signed-off-by: Wenjia Zhou <wenjiaz@nvidia.com>
Reviewed-on: http://git-master/r/1302468
Reviewed-by: Automatic_Commit_Validation_User
Reviewed-by: Esen Chen <esenc@nvidia.com>
Tested-by: Esen Chen <esenc@nvidia.com>
Reviewed-by: Jerry Chang <jerchang@nvidia.com>
Reviewed-by: Andrew Chew <achew@nvidia.com>
GVS: Gerrit_Virtual_Submit
Reviewed-by: Bhanu Murthy V <bmurthyv@nvidia.com>