IB/ipath: Fix ib_ipath driver to work with SRP

I am still working on a proposal to remove the phys_to_virt() calls
in the ib_ipath driver.  In the mean time, this patch allows SRP
to work by fixing the R_Key check and conversion from IB address
to kernel virtual address.  It also returns the correct page size
for FMRs.

Signed-off-by: Ralph Campbell <ralph.campbell@qlogic.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>