[GFS2] fs/gfs2/log.c:log_bmap() fix printk format warning

Fix a printk format warning in fs/gfs2/log.c:
fs/gfs2/log.c:322: warning: format '%llu' expects type 'long long unsigned int', but argument 3 has type 'sector_t'

Signed-off-by: Ryusuke Konishi <ryusuke@osrg.net>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>