drm/amdgpu: fix mes packet params issue when flush hdp.

drm/amdgpu: fix mes packet params issue when flush hdp.

v4:
use func "amdgpu_gfx_get_hdp_flush_mask" to get ref_and_mask for
gfx9 through gfx12.

v3:
Unify the get_ref_and_mask function in amdgpu_gfx_funcs,
to support both GFX11 and earlier generations

v2:
place "get_ref_and_mask" in amdgpu_gfx_funcs instead of amdgpu_ring,
since this function only assigns the cp entry.

v1:
both gfx ring and mes ring use cp0 to flush hdp, cause conflict.

use function get_ref_and_mask to assign the cp entry.
reassign mes to use cp8 instead.

Signed-off-by: chong li <chongli2@amd.com>
Acked-by: Lijo Lazar <lijo.lazar@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>