libv4lplugins: Report H264 Main profile only is supported

RK3399 supports H264 Base, Main and High profiles. However,
libv4lplugins support Main profile only. So, in the plugin layer,
it needs to interrupt the IOCTL and report H264 Main profile only
is supported.

BUG=b:145095115
TEST=android.media.cts.MediaRecorderTest#testProfileAvcBaselineLevel1

Change-Id: I6b050c99474a97c535b38ba6896c147728a3be25
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/libv4lplugins/+/1958319


Tested-by: Hirokazu Honda <hiroh@chromium.org>
Auto-Submit: Hirokazu Honda <hiroh@chromium.org>
Reviewed-by: Chih-Yu Huang <akahuang@chromium.org>
Reviewed-by: Alexandre Courbot <acourbot@chromium.org>
Commit-Queue: Chih-Yu Huang <akahuang@chromium.org>
Commit-Queue: Hirokazu Honda <hiroh@chromium.org>