drm/amdgpu: remove inproper workaround for vega10

the workaround is not needed for soc15 ASICs except
for vega10. it is even not needed with latest vega10
vbios.
Signed-off-by: Hawking Zhang <Hawking.Zhang@amd.com>
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -956,8 +956,6 @@ struct amdgpu_device {
 	/* s3/s4 mask */
 	bool                            in_suspend;
 
-	/* record last mm index being written through WREG32*/
-	unsigned long last_mm_index;
 	bool                            in_gpu_reset;
 	enum pp_mp1_state               mp1_state;
 	struct mutex  lock_reset;

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

@@ -387,10 +387,6 @@ void static inline amdgpu_mm_wreg_mmio(struct amdgpu_device *adev, uint32_t reg,
 		writel(v, ((void __iomem *)adev->rmmio) + (mmMM_DATA * 4));
 		spin_unlock_irqrestore(&adev->mmio_idx_lock, flags);
 	}
-
-	if (adev->asic_type >= CHIP_VEGA10 && reg == 1 && adev->last_mm_index == 0x5702C) {
-		udelay(500);
-	}
 }
 
 /**
@@ -406,10 +402,6 @@ void static inline amdgpu_mm_wreg_mmio(struct amdgpu_device *adev, uint32_t reg,
 void amdgpu_mm_wreg(struct amdgpu_device *adev, uint32_t reg, uint32_t v,
 		    uint32_t acc_flags)
 {
-	if (adev->asic_type >= CHIP_VEGA10 && reg == 0) {
-		adev->last_mm_index = v;
-	}
-
 	if ((acc_flags & AMDGPU_REGS_KIQ) || (!(acc_flags & AMDGPU_REGS_NO_KIQ) && amdgpu_sriov_runtime(adev)))
 		return amdgpu_kiq_wreg(adev, reg, v);
 
@@ -464,20 +456,12 @@ u32 amdgpu_io_rreg(struct amdgpu_device *adev, u32 reg)
  */
 void amdgpu_io_wreg(struct amdgpu_device *adev, u32 reg, u32 v)
 {
-	if (adev->asic_type >= CHIP_VEGA10 && reg == 0) {
-		adev->last_mm_index = v;
-	}
-
 	if ((reg * 4) < adev->rio_mem_size)
 		iowrite32(v, adev->rio_mem + (reg * 4));
 	else {
 		iowrite32((reg * 4), adev->rio_mem + (mmMM_INDEX * 4));
 		iowrite32(v, adev->rio_mem + (mmMM_DATA * 4));
 	}
-
-	if (adev->asic_type >= CHIP_VEGA10 && reg == 1 && adev->last_mm_index == 0x5702C) {
-		udelay(500);
-	}
 }
 
 /**