wlcore: add ACX_PEER_CAP command

wlcore: add ACX_PEER_CAP command

ACX_PEER_CAP command is just ACX_PEER_HT_CAP, but allows
configuring the peer's support rates as well.

this is needed because we start the station role when
the remote rates are not known yet.

the two commands should be unified in future fw versions,
but for now add a new set_peer_cap per-hw op, that will
use ACX_PEER_CAP for 18xx, and ACX_PEER_HT_CAP for 12xx.

Signed-off-by: Eliad Peller <eliad@wizery.com>
Signed-off-by: Arik Nemtsov <arik@wizery.com>
Signed-off-by: Luciano Coelho <coelho@ti.com>