drm/v3d: nullify pointer se with a NULL

Currently a plain integer is being used to nullify the pointer
struct v3d_submit_ext *se. Use NULL instead. Cleans up sparse
warnings:
drivers/gpu/drm/v3d/v3d_gem.c:777:53: warning: Using plain integer as
NULL pointer
drivers/gpu/drm/v3d/v3d_gem.c:1010:45: warning: Using plain integer as
NULL pointer
Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
Reviewed-by: Melissa Wen <mwen@igalia.com>
Signed-off-by: Melissa Wen <melissa.srw@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1634282081-72255-1-git-send-email-yang.lee@linux.alibaba.com

drivers/gpu/drm/v3d/v3d_gem.c

@@ -774,7 +774,7 @@ v3d_submit_cl_ioctl(struct drm_device *dev, void *data,
 
 	if (args->flags & DRM_V3D_SUBMIT_CL_FLUSH_CACHE) {
 		ret = v3d_job_init(v3d, file_priv, (void *)&clean_job, sizeof(*clean_job),
-				   v3d_job_free, 0, 0, V3D_CACHE_CLEAN);
+				   v3d_job_free, 0, NULL, V3D_CACHE_CLEAN);
 		if (ret)
 			goto fail;
 
@@ -1007,7 +1007,7 @@ v3d_submit_csd_ioctl(struct drm_device *dev, void *data,
 		goto fail;
 
 	ret = v3d_job_init(v3d, file_priv, (void *)&clean_job, sizeof(*clean_job),
-			   v3d_job_free, 0, 0, V3D_CACHE_CLEAN);
+			   v3d_job_free, 0, NULL, V3D_CACHE_CLEAN);
 	if (ret)
 		goto fail;