net/mlx4_core: Cache line EQE size support

Enable mlx4 interrupt handler to work with EQE stride feature,
The feature may be enabled when cache line is bigger than 64B.
The EQE size will then be the cache line size, and the context
segment resides in [0-31] offset.

Signed-off-by: Ido Shamay <idos@mellanox.com>
Signed-off-by: Jack Morgenstein <jackm@dev.mellanox.co.il>
Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>