[media] marvell-ccic: use internal variable replace global frame stats variable

This patch replaces the global frame stats variables by using
internal variables in mcam_camera structure.

Signed-off-by: Albert Wang <twang13@marvell.com>
Signed-off-by: Libin Yang <lbyang@marvell.com>
Acked-by: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>