isdnloop: fix and simplify isdnloop_init()

Fix a buffer overflow bug by removing the revision and printk.

[   22.016214] isdnloop-ISDN-driver Rev 1.11.6.7
[   22.097508] isdnloop: (loop0) virtual card added
[   22.174400] Kernel panic - not syncing: stack-protector: Kernel stack is corrupted in: ffffffff83244972
[   22.174400]
[   22.436157] Pid: 1, comm: swapper Not tainted 3.5.0-bisect-00018-gfa8bbb1-dirty #129
[   22.624071] Call Trace:
[   22.720558]  [<ffffffff832448c3>] ? CallcNew+0x56/0x56
[   22.815248]  [<ffffffff8222b623>] panic+0x110/0x329
[   22.914330]  [<ffffffff83244972>] ? isdnloop_init+0xaf/0xb1
[   23.014800]  [<ffffffff832448c3>] ? CallcNew+0x56/0x56
[   23.090763]  [<ffffffff8108e24b>] __stack_chk_fail+0x2b/0x30
[   23.185748]  [<ffffffff83244972>] isdnloop_init+0xaf/0xb1

Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>