bnx2x: Casting page alignment

Adding a proper cast to the argument of PAGE_ALIGN macro so that the output
won't depend on its original type. Without this cast aligned value will be
truncated to the size of the argument type.

Reported-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: Vladislav Zolotarov <vladz@broadcom.com>
Tested-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: Eilon Greenstein <eilong@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>