[media] media: videobuf2: Move vb2_fileio_data and vb2_thread to core part

[media] media: videobuf2: Move vb2_fileio_data and vb2_thread to core part

Move things related with vb2 file I/O and vb2_thread without doing any
functional changes. After that, videobuf2-internal.h is removed because
it is not necessary any more.

Signed-off-by: Junghak Sung <jh1009.sung@samsung.com>
Signed-off-by: Geunyoung Kim <nenggun.kim@samsung.com>
Acked-by: Seung-Woo Kim <sw0312.kim@samsung.com>
Acked-by: Inki Dae <inki.dae@samsung.com>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Hans Verkuil <hansverk@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>