CHROMIUM: drivers: media: virtio: stop querying level for non-H264 formats

H.264 is the only format that features a level. Querying that property
on other formats results in the following log by crosvm:

	specified format has no level: VP8
	returning error response: invalid argument

While it is not fatal, it can be confused with an actual error, so stop
querying for level on non-H264 format.

BUG=b:161774071
TEST=emerge-brya sys-kernel/arcvm-kernel-ack-5_10

Signed-off-by: Alexandre Courbot <acourbot@chromium.org>

Change-Id: Id18807859bd145d0fce533e0cf844a465095fc81
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/kernel/+/4066821


Reviewed-by: Bartłomiej Grzesik <bgrzesik@google.com>
Reviewed-by: Keiichi Watanabe <keiichiw@chromium.org>
Tested-by: Alexandre Courbot <acourbot@chromium.org>
Auto-Submit: Alexandre Courbot <acourbot@chromium.org>
Commit-Queue: Alexandre Courbot <acourbot@chromium.org>
Signed-off-by: Slawomir Rosek <srosek@google.com>