IB/mlx4: Increase the number of vectors (EQs) available for ULPs

Enable IB ULPs to use a larger portion of the device EQs (which map to
IRQs).  The mlx4_ib driver follows the mlx4_core framework of the EQs
to be divided among the device ports.  In this scheme, for each IB
port, the number of allocated EQs follows the number of cores, subject
to other system constraints, such as number available MSI-X vectors.

Signed-off-by: Shlomo Pongratz <shlomop@mellanox.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>