drm/amd/display: Add update_descriptor param info in 'update_planes_and_stream_state'

drm/amd/display: Add update_descriptor param info in 'update_planes_and_stream_state'

Add missing info for the update_descriptor parameter in
update_planes_and_stream_state().

Fixes the below with gcc W=1:
../display/dc/core/dc.c:3630 function parameter 'update_descriptor' not described in 'update_planes_and_stream_state'

Fixes: c24bb00cc6cf ("drm/amd/display: Refactor DC update checks")
Cc: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Cc: Dillon Varone <Dillon.Varone@amd.com>
Cc: Chuanyu Tseng <chuanyu.tseng@amd.com>
Cc: Roman Li <roman.li@amd.com>
Cc: Alex Hung <alex.hung@amd.com>
Cc: Tom Chung <chiahsuan.chung@amd.com>
Cc: Dan Carpenter <dan.carpenter@linaro.org>
Cc: Aurabindo Pillai <aurabindo.pillai@amd.com>
Signed-off-by: Srinivasan Shanmugam <srinivasan.shanmugam@amd.com>
Reviewed-by: Alex Hung <alex.hung@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>