mlx4_core: calculate log_num_mtt based on total system memory

mlx4_core: calculate log_num_mtt based on total system memory

The SR-IOV shared-port mechanism has a limitation that all the resources
and qp contexts are proxied through the PF. In order to reflect the
supported mtt entries, the log_num_mtt must be calculated based on the host
system memory rather than the privileged domain system memory. Thus, this
patch performs a Xen specific call to obtain the total memory during the PF
driver loading and uses that info to determine the size of the mtt table.

Orabug: 26526968

Signed-off-by: Wei Lin Guay <wei.lin.guay@oracle.com>
Signed-off-by: Ajaykumar Hotchandani <ajaykumar.hotchandani@oracle.com>
Reviewed-by: Avinash Repaka <avinash.repaka@oracle.com>
Reviewed-by: Håkon Bugge <haakon.bugge@oracle.com>