drm/amdgpu: replace kcq enable/disable functions on gfx_v9

[Why]
There are HW-indpendent functions that enables and disables kcq. These functions use
the kiq_pm4_funcs implementation.

[How]
Local kcq enable and disable functions removed and replace it by the generic kcq
enable under amdgpu_gfx

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>