msdkh265enc: add support for RGB 10bit format
The SDK can support A2RGB10 format [1], A2RGB10 format corresponds to BGR10A2_LE format in gstreamer. A2RGB10 format only supports low-power mode.
Example:
gst-launch-1.0 videotestsrc ! video/x-raw,format=BGR10A2_LE
! msdkh265enc low-power=1 ! fakesink
[1] https://github.com/Intel-Media-SDK/MediaSDK/blob/master/doc/mediasdk-man.md#mfxframedata