ext4: use ext4_fc_tl_mem in fast-commit replay path

ext4: use ext4_fc_tl_mem in fast-commit replay path

To avoid 'sparse' warnings about missing endianness conversions, don't
store native endianness values into struct ext4_fc_tl.  Instead, use a
separate struct type, ext4_fc_tl_mem.

Fixes: dcc5827484d6 ("ext4: factor out ext4_fc_get_tl()")
Cc: Ye Bin <yebin10@huawei.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20221217050212.150665-1-ebiggers@kernel.org
Signed-off-by: Theodore Ts'o <tytso@mit.edu>