mlx4_{core, ib, en}: Fix driver when sizeof (phys_addr_t) > sizeof (long)

Some systems have PCI addresses that don't fit in unsigned long (eg some
32-bit PowerPC 440 systems have 36-bit bus addresses).  Fix up mlx4 drivers
by using phys_addr_t where appropriate, so we don't truncate any PCI
resource addresses before ioremapping them.

Signed-off-by: Roland Dreier <rolandd@cisco.com>