drm/amd/display: Remove set but not unused variable 'stream_status'

drm/amd/display: Remove set but not unused variable 'stream_status'

drivers/gpu/drm/amd/amdgpu/../display/dc/dcn10/dcn10_hw_sequencer.c:
 In function dcn10_post_unlock_program_front_end:
drivers/gpu/drm/amd/amdgpu/../display/dc/dcn10/dcn10_hw_sequencer.c:2623:29:
 warning: variable stream_status set but not used [-Wunused-but-set-variable]

commit f7fd6db74c5f ("drm/amd/display: Split program front end part that occur outside lock")
involved this unused variable.

Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>