jfs: turn diLog(), dataLog() and txLog() into void functions

These functions always return '0' and no callers use the return value.
So make it a void function.

This eliminates the following coccicheck warning:
./fs/jfs/jfs_txnmgr.c:1365:5-7: Unneeded variable: "rc". Return "0" on
line 1414
./fs/jfs/jfs_txnmgr.c:1422:5-7: Unneeded variable: "rc". Return "0" on
line 1527

Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
Signed-off-by: Dave Kleikamp <dave.kleikamp@oracle.com>