powerpc: Correct page-in counter for CMM with 64k pages

powerpc: Correct page-in counter for CMM with 64k pages

Linux will report the number of page-ins so that the hypervisor can
better determine partition memory pressure.  The hardware page size
and the OS page size can be different.  In the case where the hardware
page size is 4k and the OS is running with 64k pages the code in
commit 409001948d9f221c94a61c3ee96de112755fc04d ("powerpc: Update
page-in counter for CMM") would under-report the number of pages.

This corrects the reporting to the hypervisor by incrementing the
page_in count by 1 << PAGE_FACTOR each time.

Reported-by: Andrew Theurer <habanero@linux.vnet.ibm.com>
Signed-off-by: Robert Jennings <rcj@linux.vnet.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>