UnifiedHMI: Update SRCREV for RVGPU and virtio-loopback-driver, and upgrade mesa...

UnifiedHMI: Update SRCREV for RVGPU and virtio-loopback-driver, and upgrade mesa-virtio.

- OSS RVGPU update: Support for xdg_shell.

- OSS virtio-gpu-driver update: Simplify directory structure, not use cmake.

- Recipe updates:

  1, Update SRCREV for RVGPU. Since RVGPU now supports xdg_shell in OSS, the patch enabling xdg_shell has been removed.

  2, Remove the agl-shell-desktop interface because it is planned to be phased out.

  3, Upgrade the base mesa for mesa-virtio from 18.2.0 to 20.3.5. Remove patches that were used with mesa-18.2.0. We are exploring ways to run it with the newer mesa.

  4, Update SRCREV for virtio-loopback-driver.

  5, Update meta-data for patches of RVGPU and virtio-gpu-driver. The content of the patches remains unchanged.

We are planning to support a gRPC protocol interface for RVGPU.

Bug-AGL: SPEC-4898

Change-Id: Ie314f40687c92ef93258b8fdc817584586d20e25
Signed-off-by: Fumiya Kohzu <kohzu.fumiya@jp.panasonic.com>