drm/amdgpu: Use RLCG to program GRBM_GFX_CNTL during full access time

[Why]
KIQ register init requires GRBM_GFX_CNTL to select KIQ.

[How]
As RLCG accessing registers will save the data of GRBM_GFX_CNTL and restore it.
Use RLCG indirect accessing register method to select grbm instead of mmio directly access.
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Yifan Zha <Yifan.Zha@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/soc21.c

@@ -179,7 +179,7 @@ void soc21_grbm_select(struct amdgpu_device *adev,
 	grbm_gfx_cntl = REG_SET_FIELD(grbm_gfx_cntl, GRBM_GFX_CNTL, VMID, vmid);
 	grbm_gfx_cntl = REG_SET_FIELD(grbm_gfx_cntl, GRBM_GFX_CNTL, QUEUEID, queue);
 
-	WREG32(SOC15_REG_OFFSET(GC, 0, regGRBM_GFX_CNTL), grbm_gfx_cntl);
+	WREG32_SOC15(GC, 0, regGRBM_GFX_CNTL, grbm_gfx_cntl);
 }
 
 static void soc21_vga_set_state(struct amdgpu_device *adev, bool state)