qed: Correct doorbell configuration for !4Kb pages

When configuring the doorbell DPI address, driver aligns the start
address to 4KB [HW-pages] instead of host PAGE_SIZE.
As a result, RoCE applications might receive addresses which are
unaligned to pages [when PAGE_SIZE > 4KB], which is a security risk.

Fixes: 51ff1725

 ("qed: Add support for RoCE hw init")
Signed-off-by: Ram Amrani <Ram.Amrani@cavium.com>
Signed-off-by: Yuval Mintz <Yuval.Mintz@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>