drm/amdgpu: kiq pm4 function implementation for gfx_v9

Functions implemented from kiq_pm4_funcs struct members
for gfx_v9 version.

Signed-off-by: Alex Sierra <alex.sierra@amd.com>
Acked-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>