net/mlx4_core: Set number of msix vectors under SRIOV mode to firmware defaults

[ Upstream commit ca4c7b35f75492de7fbf5ee95be07481c348caee ]

The lines

	if (mlx4_is_mfunc(dev)) {
		nreq = 2;
	} else {

which hard code the number of requested msi-x vectors under multi-function
mode to two can be removed completely, since the firmware sets num_eqs and
reserved_eqs appropriately Thus, the code line:

	nreq = min_t(int, dev->caps.num_eqs - dev->caps.reserved_eqs, nreq);

is by itself sufficient and correct for all cases. Currently, for mfunc
mode num_eqs = 32 and reserved_eqs = 28, hence four vectors will be enabled.

This triples (one vector is used for the async events and commands EQ) the
horse power provided for processing of incoming packets on netdev RSS scheme,
IO initiators/targets commands processing flows, etc.

Reviewed-by: Jack Morgenstein <jackm@dev.mellanox.co.il>
Signed-off-by: Amir Vadai <amirv@mellanox.com>
Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>