[media] media: i2c: Convert to devm_kzalloc()

Using the managed function the kfree() calls can be removed from the
probe error path and the remove handler.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Acked-by: Lad, Prabhakar <prabhakar.csengg@gmail.com>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Benoît Thébaudeau <benoit.thebaudeau@advansee.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>