This reverts commit 474f0101.

Caused a regression:

Samsung Odyssey Neo G9, running at 5120x1440@240/VRR, connected to Navi
21 via DisplayPort, blanks and the GPU hangs while starting the Steam
game Assetto Corsa Competizione (via Proton 7.0).

Example dmesg excerpt:

 amdgpu 0000:0c:00.0: [drm] ERROR [CRTC:82:crtc-0] flip_done timed out
 NMI watchdog: Watchdog detected hard LOCKUP on cpu 6
 [...]
 RIP: 0010:amdgpu_device_rreg.part.0+0x2f/0xf0 [amdgpu]
 Code: 41 54 44 8d 24 b5 00 00 00 00 55 89 f5 53 48 89 fb 4c 3b a7 60 0b 00 00 73 6a 83 e2 02 74 29 4c 03 a3 68 0b 00 00 45 8b 24 24 <48> 8b 43 08 0f b7 70 3e 66 90 44 89 e0 5b 5d 41 5c 31 d2 31 c9 31
 RSP: 0000:ffffb39a119dfb88 EFLAGS: 00000086
 RAX: ffffffffc0eb96a0 RBX: ffff9e7963dc0000 RCX: 0000000000007fff
 RDX: 0000000000000000 RSI: 0000000000004ff6 RDI: ffff9e7963dc0000
 RBP: 0000000000004ff6 R08: ffffb39a119dfc40 R09: 0000000000000010
 R10: ffffb39a119dfc40 R11: ffffb39a119dfc44 R12: 00000000000e05ae
 R13: 0000000000000000 R14: ffff9e7963dc0010 R15: 0000000000000000
 FS:  000000001012f6c0(0000) GS:ffff9e805eb80000(0000) knlGS:000000007fd40000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: 00000000461ca000 CR3: 00000002a8a20000 CR4: 0000000000350ee0
 Call Trace:
  <TASK>
  dm_read_reg_func+0x37/0xc0 [amdgpu]
  generic_reg_get2+0x22/0x60 [amdgpu]
  optc1_get_crtc_scanoutpos+0x6a/0xc0 [amdgpu]
  dc_stream_get_scanoutpos+0x74/0x90 [amdgpu]
  dm_crtc_get_scanoutpos+0x82/0xf0 [amdgpu]
  amdgpu_display_get_crtc_scanoutpos+0x91/0x190 [amdgpu]
  ? dm_read_reg_func+0x37/0xc0 [amdgpu]
  amdgpu_get_vblank_counter_kms+0xb4/0x1a0 [amdgpu]
  dm_pflip_high_irq+0x213/0x2f0 [amdgpu]
  amdgpu_dm_irq_handler+0x8a/0x200 [amdgpu]
  amdgpu_irq_dispatch+0xd4/0x220 [amdgpu]
  amdgpu_ih_process+0x7f/0x110 [amdgpu]
  amdgpu_irq_handler+0x1f/0x70 [amdgpu]
  __handle_irq_event_percpu+0x46/0x1b0
  handle_irq_event+0x34/0x80
  handle_edge_irq+0x9f/0x240
  __common_interrupt+0x66/0x110
  common_interrupt+0x5c/0xd0
  asm_common_interrupt+0x22/0x40
Reviewed-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Michel Dänzer <mdaenzer@redhat.com>
Signed-off-by: Hamza Mahfooz <hamza.mahfooz@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>