erofs-utils: fix Makefile for the erofsfuse manpage

Add the missing dependency for the erofsfuse manpage.

Link: https://lore.kernel.org/r/20210516105601.711-1-xiang@kernel.org
Fixes: c952430a8ce0 ("erofs-utils: manpage: add manual for erofsfuse")
Signed-off-by: Gao Xiang <xiang@kernel.org>
1 file changed