Update checkpoint.c includes to use ext4_uboot.h compatibility layer.
Add jbd2/Makefile and include jbd2 in the build via fs/Makefile
Add necessary stubs and definitions:
- JBD2 trace stubs (trace_jbd2_checkpoint, etc.)
- mutex_lock_io, write_dirty_buffer, spin_needbreak stubs
- bd_dev field to struct block_device
- Temporary JBD2 function stubs until other jbd2 files are added
Co-developed-by: Claude Opus 4.5 <noreply@anthropic.com>
Signed-off-by: Simon Glass <simon.glass@canonical.com>
c113b81eab