f2fs: avoid f2fs_bug_on if f2fs_get_meta_page_nofail got EIO

This patch avoids BUG_ON when f2fs_get_meta_page_nofail got EIO during
xfstests/generic/475.

Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Change-Id: Ie1e9ed9acb6413fec869c3f7ca8ba1f9d7e964c7
Git-commit: edc55aaf0d1712b54a3704dd58423c7e495534fe
Git-repo: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git


Signed-off-by: Ritesh Harjani <riteshh@codeaurora.org>