[amdgpu] Regression - display does not wake on 5.8.2

Single HP Z27 display connected via DP to RX 5500 XT no longer wakes from sleep when providing stimulus (i.e., moving mouse). Works fine on 5.8.1. Manually turning off the display and then turning it back on restores normal function until next idle timeout and display sleep.

System:    Host: zen Kernel: 5.8.2 x86_64 bits: 64 compiler: N/A Desktop: GNOME 3.36.5 tk: GTK 3.24.22 wm: gnome-shell 
           dm: GDM3 Distro: Debian GNU/Linux bullseye/sid 
CPU:       Topology: 8-Core model: AMD Ryzen 7 3700X bits: 64 type: MT MCP arch: Zen 2 L2 cache: 4096 KiB 
           flags: avx avx2 lm nx pae sse sse2 sse3 sse4_1 sse4_2 sse4a ssse3 svm bogomips: 115196 
           Speed: 2199 MHz min/max: 2200/3600 MHz Core speeds (MHz): 1: 2197 2: 2194 3: 2195 4: 2192 5: 2197 6: 2191 7: 2196 
           8: 2199 9: 2198 10: 2199 11: 2200 12: 2199 13: 2198 14: 2199 15: 2199 16: 2199 
Graphics:  Device-1: Advanced Micro Devices [AMD/ATI] Navi 14 [Radeon RX 5500/5500M / Pro 5500M] vendor: Micro-Star MSI 
           driver: amdgpu v: kernel bus ID: 28:00.0 chip ID: 1002:7340 
           Display: wayland server: X.Org 1.20.8 compositor: gnome-shell driver: ati,radeon,vesa unloaded: fbdev,modesetting 
           resolution: 3840x2160~60Hz s-dpi: 163 
           OpenGL: renderer: Radeon RX 5500 XT (NAVI14 DRM 3.38.0 5.8.2 LLVM 10.0.1) v: 4.6 Mesa 20.1.5 direct render: Yes