drm/amd/display: Add Replay capability and state in debugfs

[Why & How]
User can get the panel replay capability and state for debug.

sudo cat /sys/kernel/debug/dri/0/eDP-1/replay_capability
"Sink support: no" - if panel doesn't support Replay
"Sink support: yes" - if panel supports Replay
"Driver support: no\n" - if driver doesn't support Replay
"Driver support: yes\n" - if driver supports Replay

sudo cat /sys/kernel/debug/dri/0/eDP-1/replay_state
It will return current panel replay state

Reviewed-by: Sun peng Li <sunpeng.li@amd.com>
Acked-by: Tom Chung <chiahsuan.chung@amd.com>
Signed-off-by: Tom Chung <chiahsuan.chung@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>