add missing spaces

The parameters "--debug-cache" and path are close to each other, eg:

01-09 17:14:52.058   648   648 I vold    : [libfs_mgr]Running
/system/bin/fsck.f2fs -a -c 10000 --debug-cache/dev/block/dm-10

Add a space between them to separate.

Signed-off-by: jiahao <jiahao@xiaomi.com>
Change-Id: Ie2929b541d5907a521c7b97aaed31fdca381fc1a