jfs: clean up some compiler warnings

jfs has a few variables being set but never used.

Signed-off-by: Dave Kleikamp <dave.kleikamp@oracle.com>

diff --cc fs/jfs/jfs_dmap.c
Simple merge

diff --cc fs/jfs/jfs_txnmgr.c
Simple merge

diff --cc fs/jfs/namei.c
Simple merge