[IOAT]: drivers/dma/iovlock.c: make num_pages_spanned() static

This patch makes the needlessly global num_pages_spanned() static.

Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: David S. Miller <davem@davemloft.net>