net/mlx4_core: Limit count field to 24 bits in qp_alloc_res

Some VF drivers use the upper byte of "param1" (the qp count field)
in mlx4_qp_reserve_range() to pass flags which are used to optimize
the range allocation.

Under the current code, if any of these flags are set, the 32-bit
count field yields a count greater than 2^24, which is out of range,
and this VF fails.

As these flags represent a "best-effort" allocation hint anyway, they may
safely be ignored. Therefore, the PF driver may simply mask out the bits.

Fixes: c82e9aa0

 "mlx4_core: resource tracking for HCA resources used by guests"
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>