Updates to backing store APIs, QoS profiles, and push buffer initial
index support.

Since the new HWRM_FUNC_BACKING_STORE_CFG message size has increased,
we need to add some compat. logic to fall back to the smaller legacy
size if firmware cannot accept the larger message size.  The new fields
added to the structure are not used yet.
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Acked-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>