mxc: vpu: Fix a build error VFL_TYPE_GRABBER is not defined

Refer to commit dc42cf74("media: v4l2-dev.h: remove VFL_TYPE_GRABBER")
VFL_TYPE_GRABBER has been removed and replaced with VFL_TYPE_VIDEO

Signed-off-by: Xiaolei Wang <xiaolei.wang@windriver.com>
Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>