[ofa-general] proper use of dev_attr->page_size_cap

[Roland Dreier]

 > It would also be nice if we could instead do this:
 > 
 > rds_ibdev->fmr_page_shift = PAGE_SHIFT;

Yes, I think it is safe to assume that a device can handle a page size
matching the native system's page size.  The other sizes are there if
they help (eg 512 byte pages are good for doing block storage traffic
with 512-byte sectors)

 - R.