f2fs: fix to detect failure of dquot_initialize

dquot_initialize() can fail due to any exception inside quota subsystem,
f2fs needs to be aware of it, and return correct return value to caller.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>