bnx2x: Using system page size for SGE

When the page size is not 4KB, the FW must be programmed to work with
the right SGE boundaries and fragment list length.

To avoid confusion with the BCM_PAGE_SIZE which is set to 4KB for the
FW sake, another alias for the system page size was added to
explicitly indicate that it is meant for the SGE

Signed-off-by: Eilon Greenstein <eilong@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>