f2fs: fix to bail out in get_new_segment()

In the Linux kernel, the following vulnerability has been resolved:

f2fs: fix to bail out in get_new_segment()

------------[ cut here ]------------

WARNING: CPU: 3 PID: 579 at fs/f2fs/segment.c:2832 new_curseg+0x5e8/0x6dc

pc : new_curseg+0x5e8/0x6dc

Call trace:

new_curseg+0x5e8/0x6dc

f2fs_allocate_data_block+0xa54/0xe28

do_write_page+0x6c/0x194

f2fs_do_write_node_page+0x38/0x78

__write_node_page+0x248/0x6d4

f2fs_sync_node_pages+0x524/0x72c

f2fs_write_checkpoint+0x4bc/0x9b0

__checkpoint_and_complete_reqs+0x80/0x244

issue_checkpoint_thread+0x8c/0xec

kthread+0x114/0x1bc

ret_from_fork+0x10/0x20

get_new_segment() detects inconsistent status in between free_segmap

and free_secmap, let's record such error into super block, and bail

out get_new_segment() instead of continue using the segment.