drm/amd/display: Add IPS residency info to debugfs

drm/amd/display: Add IPS residency info to debugfs

[Why]
For debugging and testing purpose

[How]
Usage:
- echo 1 > /sys/kernel/debug/dri/0/amdgpu_dm_ips_residency_cntl
- echo 0 > /sys/kernel/debug/dri/0/amdgpu_dm_ips_residency_cntl
- cat /sys/kernel/debug/dri/0/amdgpu_dm_ips_residency

Reviewed-by: ChiaHsuan (Tom) Chung <chiahsuan.chung@amd.com>
Signed-off-by: Ray Wu <ray.wu@amd.com>
Signed-off-by: Matthew Stewart <matthew.stewart2@amd.com>
Tested-by: Dan Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>