As NR_CPUS might be > 128, and every spining CPU decrements the lock, we need 
to use more than 8 bits for a spinlock. The current (i386/x86_64) 
implementations have a (theorical) bug in this area.
As the allocated space for spinlock_t is 32 bits, let's use full 32 bits and 
let the CPUS fight :)

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>