Revert "drm/amdgpu: use the BAR if possible in amdgpu_device_vram_access v2"

Revert "drm/amdgpu: use the BAR if possible in amdgpu_device_vram_access v2"

This reverts commit c12b84d6e0d70f1185e6daddfd12afb671791b6e.

The original patch causes a RAS event and subsequent kernel hard-hang
when running the KFDMemoryTest.PtraceAccessInvisibleVram on VG20 and
Arcturus

dmesg output at hang time:
[drm] RAS event of type ERREVENT_ATHUB_INTERRUPT detected!
amdgpu 0000:67:00.0: GPU reset begin!
Evicting PASID 0x8000 queues
Started evicting pasid 0x8000
qcm fence wait loop timeout expired
The cp might be in an unrecoverable state due to an unsuccessful queues preemption
Failed to evict process queues
Failed to suspend process 0x8000
Finished evicting pasid 0x8000
Started restoring pasid 0x8000
Finished restoring pasid 0x8000
[drm] UVD VCPU state may lost due to RAS ERREVENT_ATHUB_INTERRUPT
amdgpu: [powerplay] Failed to send message 0x26, response 0x0
amdgpu: [powerplay] Failed to set soft min gfxclk !
amdgpu: [powerplay] Failed to upload DPM Bootup Levels!
amdgpu: [powerplay] Failed to send message 0x7, response 0x0
amdgpu: [powerplay] [DisableAllSMUFeatures] Failed to disable all smu features!
amdgpu: [powerplay] [DisableDpmTasks] Failed to disable all smu features!
amdgpu: [powerplay] [PowerOffAsic] Failed to disable DPM!
[drm:amdgpu_device_ip_suspend_phase2 [amdgpu]] *ERROR* suspend of IP block <powerplay> failed -5

Signed-off-by: Kent Russell <kent.russell@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>