drm/amdgpu:Support new VCN FW version naming convention

Support new VCN FW version naming convention:
  [31, 28] for VEP interface major version if applicable
  [27, 24] for decode interface major version
  [23, 20] for encode interface major version
  [19, 12] for encode interface minor version
  [11, 0]  for firmware revision
Bit 20-23, it is encode major and non-zero for new naming convention.
This field is part of version minor and DRM_DISABLED_FLAG in old naming
convention. Since the latest version minor is 0x5B and DRM_DISABLED_FLAG
is zero in old naming convention, this field is always zero so far.
These four bits are used to tell which naming convention is present.

Signed-off-by: James Zhu <James.Zhu@amd.com>
Reviewed-by: Fang, Peter <Peter.Fang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>