f2fs: fix to do sanity check on segment type in build_sit_entries()

f2fs: fix to do sanity check on segment type in build_sit_entries()

As Wenqing Liu <wenqingliu0120@gmail.com> reported in bugzilla:

https://bugzilla.kernel.org/show_bug.cgi?id=216285

RIP: 0010:memcpy_erms+0x6/0x10
 f2fs_update_meta_page+0x84/0x570 [f2fs]
 change_curseg.constprop.0+0x159/0xbd0 [f2fs]
 f2fs_do_replace_block+0x5c7/0x18a0 [f2fs]
 f2fs_replace_block+0xeb/0x180 [f2fs]
 recover_data+0x1abd/0x6f50 [f2fs]
 f2fs_recover_fsync_data+0x12ce/0x3250 [f2fs]
 f2fs_fill_super+0x4459/0x6190 [f2fs]
 mount_bdev+0x2cf/0x3b0
 legacy_get_tree+0xed/0x1d0
 vfs_get_tree+0x81/0x2b0
 path_mount+0x47e/0x19d0
 do_mount+0xce/0xf0
 __x64_sys_mount+0x12c/0x1a0
 do_syscall_64+0x38/0x90
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

The root cause is segment type is invalid, so in f2fs_do_replace_block(),
f2fs accesses f2fs_sm_info::curseg_array with out-of-range segment type,
result in accessing invalid curseg->sum_blk during memcpy in
f2fs_update_meta_page(). Fix this by adding sanity check on segment type
in build_sit_entries().

Reported-by: Wenqing Liu <wenqingliu0120@gmail.com>
Signed-off-by: Chao Yu <chao.yu@oppo.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>