drm/amd/display: PSR eDP p-state warning occurs intermittently after unplug DP

[Why]
with eDP + DP, each display use one pipe. after DP unplugged, eDP switch
from one pipe to two pipes -- pipe split.  dpp1_cm_set_regamma_pwl will
be executed too. The duration from switch single pipe to dual pipes is a
little long which could let eDP enter PSR mode. upon two pipes for eDP
are setup, eDP PHY is disabled. front pipe is not really running to
fetch data from frame buffer. i.e., dchubp is not in normal working
status. execution of hubbub1_wm_change_req_wa may cause p-state warning.

[How]
disable eDP PSR before dc_commit_state. psr is disabled when execute
hubbub1_wm_change_req_wa.

Signed-off-by: Hersen Wu <hersenxs.wu@amd.com>
Reviewed-by: Roman Li <Roman.Li@amd.com>
Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>