bcachefs: Fix type for parameter in journal_advance_devs_to_next_bucket

Replace u64 with __le64 to match the expected parameter type. Ensure consistency both in function calls and within the function itself.

Signed-off-by: Gabriel Shahrouzi <gshahrouzi@gmail.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>