drm/amdgpu: add number of mec for Arcturus

MEC is the CP compute microcontroller.
Signed-off-by: Le Ma <le.ma@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c

@@ -1673,6 +1673,7 @@ static int gfx_v9_0_sw_init(void *handle)
 	case CHIP_VEGA12:
 	case CHIP_VEGA20:
 	case CHIP_RAVEN:
+	case CHIP_ARCTURUS:
 		adev->gfx.mec.num_mec = 2;
 		break;
 	default: