[JFFS2] fix printk warning in jffs2_block_check_erase()

fs/jffs2/erase.c: In function 'jffs2_block_check_erase':
fs/jffs2/erase.c:355: warning: format '%08x' expects type 'unsigned int', but argument 3 has type 'long unsigned int'

and

fs/jffs2/erase.c: In function 'jffs2_erase_pending_blocks':
fs/jffs2/erase.c:404: warning: 'bad_offset' may be used uninitialized in this function

Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: David Woodhouse <dwmw2@infradead.org>