In U-Boot, filesystems may be mounted and unmounted multiple times in a
single session. The JBD2 global state (caches) was only initialized once
and never cleaned up, preventing proper reinitialization.
Add jbd2_journal_exit_global() to properly destroy caches and reset the
initialization flag. This allows the JBD2 subsystem to be cleanly
reinitialized on subsequent mounts.
Co-developed-by: Claude Opus 4.5 <noreply@anthropic.com>
Signed-off-by: Simon Glass <simon.glass@canonical.com>