Add max MAD size to the device immutable data set and have all drivers that
support MADs report the current IB MAD size (IB_MGMT_MAD_SIZE) to the core.

Verify MAD size data in both the MAD core and when reading the immutable data.

OPA drivers will report alternate MAD sizes in subsequent patches.
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>