drm/amd/display: Fix up kdoc format for 'dc_set_edp_power'

drm/amd/display: Fix up kdoc format for 'dc_set_edp_power'

Fixes the following W=1 kernel build warning:

drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc.c:5261: warning: Cannot understand  *******************************************

Cc: Ian Chen <ian.chen@amd.com>
Cc: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Cc: Harry Wentland <harry.wentland@amd.com>
Cc: Aurabindo Pillai <aurabindo.pillai@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Srinivasan Shanmugam <srinivasan.shanmugam@amd.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>