V4L/DVB (11110): au8522/au0828: Fix Kconfig dependencies

au8522 is now dependent of V4L2, as reported by Randy Dunlap
<randy.dunlap@oracle.com>:

au8522_decoder.c:(.text+0x199898): undefined reference to `v4l2_ctrl_query_fill'
au8522_decoder.c:(.text+0x1998b3): undefined reference to `v4l2_ctrl_query_fill'
au8522_decoder.c:(.text+0x199944): undefined reference to `v4l2_device_unregister_subdev'
au8522_decoder.c:(.text+0x19997c): undefined reference to `v4l2_chip_ident_i2c_client'
au8522_decoder.c:(.text+0x199f1e): undefined reference to `v4l2_i2c_subdev_init'

Cc: Devin Heitmueller <devin.heitmueller@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>