Call init_timer() for ISDN PPP CCP reset state timer (CVE-2006-5749)

The function isdn_ppp_ccp_reset_alloc_state() sets ->timer.function
and ->timer.data and later on calls add_timer() with no init_timer()
ever done.

Noted by Al Viro.

Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Adrian Bunk <bunk@stusta.de>