iwlwifi: pcie: support rx structures for 22560 devices

The rfh for 22560 devices has changed so it supports now
the same arch of using used and free lists, but different
structures to support the last.
Use the new structures, hw dependent, to manage the lists.

bd, the free list, uses the iwl_rx_transfer_desc,
in which the vid is stored in the structs' rbid
field, and the page address in the addr field.

used_bd, the used list, uses the iwl_rx_completion_desc
struct, in which the vid is stored in the structs' rbid
field.

rb_stts, the hw "write" pointer of rx is stored in a
__le16 array, in which each entry represents the write
pointer per queue.

Signed-off-by: Golan Ben Ami <golan.ben.ami@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>