[pxc] smp 2.4.x oops

[Alessandro Rubini]

> I've got the following opps from serial console duing "insmod ./pxc.o"

Ok, it's reproducible with SMP kernel on UP computer. Not an oops
but rather a lock.

> NMI Watchdog detected LOCKUP on CPU1, registers: 

Ok,it's the same.

> Code: 7e f8 e9 e8 cf ff ff 80 7b 14 00 f3 90 7e f8 e9 19 d5 ff ff

Matches "objdump -d" of .text.lock section.

The fix: add
        spin_lock_init(&ptr->lock);
after
        init_waitqueue_head(&ptr->seq_queue);
(after allocation, before using the lock)

Will commit to CVS tomorrow.