[PATCH] remove unused blkp field in percpu_data

I found that blkp field was not used in kernel tree.

As most of the times NR_CPUS is a power of two and kmalloc() memory blocks 
too, this extra field basically doubles the memory space allocated in 
__alloc_percpu() to store the 'struct percpu_data'

(for example, if NR_CPUS=8 on i386, kmalloc(4*8+4) returns a 64 bytes block 
instead of a 32 bytes block after this patch)


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