erofs: get rid of a useless DBG_BUGON

`err` could be -EINTR and it should not be the case.  Actually such
DBG_BUGON is useless.
Reviewed-by: Chao Yu <chao@kernel.org>
Link: https://lore.kernel.org/r/20230309053148.9223-2-hsiangkao@linux.alibaba.comSigned-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>

fs/erofs/zmap.c

@@ -757,9 +757,6 @@ int z_erofs_map_blocks_iter(struct inode *inode, struct erofs_map_blocks *map,
 	err = z_erofs_do_map_blocks(inode, map, flags);
 out:
 	trace_z_erofs_map_blocks_iter_exit(inode, map, flags, err);
-
-	/* aggressively BUG_ON iff CONFIG_EROFS_FS_DEBUG is on */
-	DBG_BUGON(err < 0 && err != -ENOMEM);
 	return err;
 }