UPSTREAM: f2fs: zone: fix to wait completion of last bio in zone correctly

It needs to check last zone_pending_bio and wait IO completion before
traverse next fio in io->io_list, otherwise, bio in next zone may be
submitted before all IO completion in current zone.

Bug: 254441685
Fixes: e067dc3c ("f2fs: maintain six open zones for zoned devices")
Cc: Daeho Jeong <daehojeong@google.com>
Signed-off-by: Chao Yu <chao@kernel.org>
Reviewed-by: Daeho Jeong <daehojeong@google.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
(cherry picked from commit 536af821)
Signed-off-by: Lee Jones <joneslee@google.com>
Change-Id: Ifefc2c6fbda3aae00cef3650cafe48b496da65ca