drm/amdgpu: init mes ucode name for gfx v12

Keep gfx v12 mes fw name to gc_12_x_x_mes.bin
and gc_12_x_x_mes1.bin.

Signed-off-by: Likun Gao <Likun.Gao@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>