drm/amd/amdgpu: Port GMC v6 driver to new SI headers (v2)

Port the GMC v6 driver over to the new SI headers.

Tested with a Tahiti SI ASIC.

(v2) Fixed a couple of typos (in commented code) and moved
     defines to si_enums.h
Signed-off-by: NTom St Denis <tom.stdenis@amd.com>
Reviewed-by: NAlex Deucher <alexander.deucher@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/si_enums.h

@@ -23,6 +23,14 @@
 #ifndef SI_ENUMS_H
 #define SI_ENUMS_H
 
+#define AMDGPU_NUM_OF_VMIDS                     8
+#define SI_CRTC0_REGISTER_OFFSET                0
+#define SI_CRTC1_REGISTER_OFFSET                0x300
+#define SI_CRTC2_REGISTER_OFFSET                0x2600
+#define SI_CRTC3_REGISTER_OFFSET                0x2900
+#define SI_CRTC4_REGISTER_OFFSET                0x2c00
+#define SI_CRTC5_REGISTER_OFFSET                0x2f00
+
 #define DMA0_REGISTER_OFFSET 0x000
 #define DMA1_REGISTER_OFFSET 0x200
 #define ES_AND_GS_AUTO       3