qed: aRFS infrastructure support

This patch adds necessary APIs to interface with
qede aRFS support in successive patch.

It also reserves separate PTT entry for aRFS,
[as being in fastpath flow] for hardware access instead of
trying to acquire it at run time from the ptt pool.

Signed-off-by: Manish Chopra <manish.chopra@cavium.com>
Signed-off-by: Yuval Mintz <yuval.mintz@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>