iwlwifi: mvm: Allow P2P Device to use an existing PHY context

The patch is an optimization, that eliminates unnecessary binding
context switching and allows the P2P Device MAC to use the same channel
as an existing netdev interface.

For each ROC call, check if there is already a channel/phy context that
can be used for the P2P Device. If such channel is found, unbind
the P2P Device from its current phy context, and bind it to the already
used channel/phy context. In case that the phy context is shared,
and there is a need to change it, create a new phy context, unbind and
create a new binding.

Signed-off-by: Ilan Peer <ilan.peer@intel.com>
Reviewed-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>