mlx4_core: Fix min() warning

Fix

    drivers/net/mlx4/profile.c: In function `mlx4_make_profile':
    drivers/net/mlx4/profile.c:110: warning: comparison of distinct pointer types lacks a cast

This happened because num_possible_cpus() was secretly changed by
commit ae7a47e7

 ("cpumask: make cpumask.h eat its own dogfood.") from
returning "int" to (now) returning "unsigned int".  I think that was a
good change, so we should just swallow the fallout.

Cc: "David S. Miller" <davem@davemloft.net>
Cc: Roland Dreier <rolandd@cisco.com>
Cc: Yevgeny Petrilin <yevgenyp@mellanox.co.il>
Cc: Jack Morgenstein <jackm@dev.mellanox.co.il>
Cc: Vladimir Sokolovsky <vlad@mellanox.co.il>
Cc: Michael S. Tsirkin <mst@dev.mellanox.co.il>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Roland Dreier <rolandd@cisco.com>