drm/amd/display: use true, false for bool variable in dc_link_ddc.c

Fixes coccicheck warning:

drivers/gpu/drm/amd/display/dc/core/dc_link_ddc.c:593:6-9: WARNING: Assignment of 0/1 to bool variable
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: zhengbin <zhengbin13@huawei.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/core/dc_link_ddc.c

@@ -590,7 +590,7 @@ bool dal_ddc_submit_aux_command(struct ddc_service *ddc,
 		struct aux_payload *payload)
 {
 	uint32_t retrieved = 0;
-	bool ret = 0;
+	bool ret = false;
 
 	if (!ddc)
 		return false;