drm/amd/pm: add vcn/jepg enable functions for yellow carp

This patch is to add vcn/jepg enable functions to power up/down them
with smu messages. VCN/JEPG are poweroff by default.

Signed-off-by: Huang Rui <ray.huang@amd.com>
Reviewed-by: James Zhu <James.Zhu@amd.com>
Tested-by: James Zhu <James.Zhu@amd.com>
Reviewed-by: Leo Liu <leo.liu@amd.com>
Reviewed-by: Aaron Liu <aaron.liu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>