Revert "CHROMIUM: media: virtio: remove current_frame field from stream struct"

This reverts commit 9c43883f.

Reason for revert: broke CTS b/243319006

Original change's description:
> CHROMIUM: media: virtio: remove current_frame field from stream struct
>
> Field current_frame was used to store currently used stream format
> information provided by hypervisor. It was originaly set by
> virtio_video_try_fmt function. This function is used to check if
> provided format can be handled by the device. Same functionality is
> expected from currently unsupported VIDIOC_TRY_FMT. This function modified
> state of the driver, which is forbiden by spec for this ioctl.
> The field was used only in VIDIOC_S_PARM implementation for encoder.
>
> This patch removes current_frame field, by introducing new function
> (virtio_video_find_format). These changes are needed for future support
> for VIDIOC_TRY_FMT and to fix VIDIOC_S_PARM. Both are causing
> v4l2-compliance to fail. With this patch VIDIOC_S_PARM will no
> longer fail in early stages of encoder (before VIDIOC_S_FMT call).
>
> Signed-off-by: Bartłomiej Grzesik <bag@semihalf.com>
>
> BUG=b:160440787
> TEST=v4l2-compliance -d /dev/video0
> TEST=v4l2-compliance -d /dev/video1
> TEST=tast run eve arc.Video*
>
> Change-Id: I9fc3ef0f320125be027a824092fc6d594d698473
> Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/kernel/+/3423528


> Commit-Queue: Bartłomiej Grzesik <bgrzesik@google.com>
> Tested-by: Patryk Busse <pbu@semihalf.com>
> Reviewed-by: Alexandre Courbot <acourbot@chromium.org>
> Reviewed-by: Patryk Busse <pbu@semihalf.com>
> Tested-by: Bartłomiej Grzesik <bag@semihalf.com>

BUG=b:160440787
BUG=b:243319006
TEST=android.video.cts.VideoEncoderDecoderTest#testAvcOther0Perf0320x0240

Change-Id: If85063b1e6e6320f42d3e419e64bd0457f5f586d
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/kernel/+/3849482


Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Reviewed-by: Kazuhiro Inaba <kinaba@chromium.org>
Tested-by: Shao-Chuan Lee <shaochuan@chromium.org>
Commit-Queue: Shao-Chuan Lee <shaochuan@chromium.org>