erofs: avoid unnecessary variable `err'

variable `err' in z_erofs_submit_queue() isn't useful
here, remove it instead.
Reviewed-by: NChao Yu <yuchao0@huawei.com>
Link: https://lore.kernel.org/r/20200919072730.24989-1-hsiangkao@redhat.comSigned-off-by: NGao Xiang <hsiangkao@redhat.com>

fs/erofs/zdata.c

@@ -1190,7 +1190,6 @@ static void z_erofs_submit_queue(struct super_block *sb,
 
 		do {
 			struct page *page;
-			int err;
 
 			page = pickup_page_for_submission(pcl, i++, pagepool,
 							  MNGD_MAPPING(sbi),
@@ -1216,8 +1215,7 @@ static void z_erofs_submit_queue(struct super_block *sb,
 				++nr_bios;
 			}
 
-			err = bio_add_page(bio, page, PAGE_SIZE, 0);
-			if (err < PAGE_SIZE)
+			if (bio_add_page(bio, page, PAGE_SIZE, 0) < PAGE_SIZE)
 				goto submit_bio_retry;
 
 			last_index = cur;