i2c-dev.c utilizes memdup_user() to copy a userspace array. This is done
without an overflow check.

Use the new wrapper memdup_array_user() to copy the array more safely.
Suggested-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Philipp Stanner <pstanner@redhat.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>