net/bnx2x: Use is_kdump_kernel() to detect kdump kernel

Use is_kdump_kernel() to detect kdump kernel, instead of
reset_devices.

CC: Ariel Elior <ariel.elior@qlogic.com>
CC: Michal Schmidt <mschmidt@redhat.com>
Signed-off-by: Amir Vadai <amirv@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>