drm/amd/display/dc/link/protocols/link_dp_capability: Remove unused variable...

drm/amd/display/dc/link/protocols/link_dp_capability: Remove unused variable and mark another as __maybe_unused

‘ds_port’ is clearly not used anywhere and ‘result_write_min_hblank’ is
only utilised when debugging is enabled.  The alternative would be to
allocate the variable under the same clause as the debugging code, but
that would become very messy, very quickly.

Fixes the following W=1 kernel build warning(s):

 drivers/gpu/drm/amd/amdgpu/../display/dc/link/protocols/link_dp_capability.c: In function ‘dp_wa_power_up_0010FA’:
 drivers/gpu/drm/amd/amdgpu/../display/dc/link/protocols/link_dp_capability.c:280:42: warning: variable ‘ds_port’ set but not used [-Wunused-but-set-variable]
 drivers/gpu/drm/amd/amdgpu/../display/dc/link/protocols/link_dp_capability.c: In function ‘dpcd_set_source_specific_data’:
 drivers/gpu/drm/amd/amdgpu/../display/dc/link/protocols/link_dp_capability.c:1296:32: warning: variable ‘result_write_min_hblank’ set but not used [-Wunused-but-set-variable]

Cc: Harry Wentland <harry.wentland@amd.com>
Cc: Leo Li <sunpeng.li@amd.com>
Cc: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: "Christian König" <christian.koenig@amd.com>
Cc: "Pan, Xinhui" <Xinhui.Pan@amd.com>
Cc: David Airlie <airlied@gmail.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Wenjing Liu <wenjing.liu@amd.com>
Cc: amd-gfx@lists.freedesktop.org
Cc: dri-devel@lists.freedesktop.org
Signed-off-by: Lee Jones <lee@kernel.org>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_capability.c

@@ -1284,7 +1284,7 @@ bool dp_overwrite_extended_receiver_cap(struct dc_link *link)
 void dpcd_set_source_specific_data(struct dc_link *link)
 {
 	if (!link->dc->vendor_signature.is_valid) {
-		enum dc_status result_write_min_hblank = DC_NOT_SUPPORTED;
+		enum dc_status __maybe_unused result_write_min_hblank = DC_NOT_SUPPORTED;
 		struct dpcd_amd_signature amd_signature = {0};
 		struct dpcd_amd_device_id amd_device_id = {0};