mlx4_core: Extend num_mtt in dev caps to avoid overflow.

mlx4_core: Extend num_mtt in dev caps to avoid overflow.

Some legitimate combinations of log_num_mtt and log_mtts_per_seg
cause overflow in the calculation of the num_mtt when initializing
the HCA which causes Kernel panic. Changed the variable to be 'u64'
instead of 'int' to avoid the overflow and made the needed changes
to support the new type.

Signed-off-by: Majd Dibbiny <majd@mellanox.com>
(Ported from Mellanox OFED 2.4)

Signed-off-by: Mukesh Kacker <mukesh.kacker@oracle.com>