bcachefs: Add empty statement between label and declaration in check_inode_hash_info_...

bcachefs: Add empty statement between label and declaration in check_inode_hash_info_matches_root()

Clang 18 and newer warns (or errors with CONFIG_WERROR=y):

  fs/bcachefs/str_hash.c:164:2: error: label followed by a declaration is a C23 extension [-Werror,-Wc23-extensions]
    164 |         struct bch_inode_unpacked inode;
        |         ^

In Clang 17 and prior, this is an unconditional hard error:

  fs/bcachefs/str_hash.c:164:2: error: expected expression
    164 |         struct bch_inode_unpacked inode;
        |         ^
  fs/bcachefs/str_hash.c:165:30: error: use of undeclared identifier 'inode'
    165 |         ret = bch2_inode_unpack(k, &inode);
        |                                     ^
  fs/bcachefs/str_hash.c:169:55: error: use of undeclared identifier 'inode'
    169 |         struct bch_hash_info hash2 = bch2_hash_info_init(c, &inode);
        |                                                              ^
  fs/bcachefs/str_hash.c:171:40: error: use of undeclared identifier 'inode'
    171 |                 ret = repair_inode_hash_info(trans, &inode);
        |                                                      ^

Add an empty statement between the label and the declaration to fix the
warning/error without disturbing the code too much.

Fixes: 2519d3b0d656 ("bcachefs: bch2_str_hash_check_key() now checks inode hash info")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202412092339.QB7hffGC-lkp@intel.com/
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>