cnic,bnx2i,bnx2fc: Fix inconsistent use of page size

The bnx2/bnx2x rings are made up of linked pages.  However there is an
upper limit on the page size as some the page size settings are 16-bit
in the hardware/firmware interface.  In the current code, some parts
use BNX2_PAGE_SIZE which has a 16K upper limit and some parts use
PAGE_SIZE.  On archs with >= 64K PAGE_SIZE, it generates some compile
warnings.  Define a new CNIC_PAGE_SZIE which has an upper limit of
16K and use it consistently in all relevant parts.

Signed-off-by: Michael Chan <mchan@broadcom.com>
Signed-off-by: Eddie Wai <eddie.wai@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>