wifi: iwlwifi: mvm: fix the PHY context resolution for p2p device

We seem to have an issue in case we had a BSS and a P2P device on
channel 1 and then, the P2P device gets an ROC on channel 6. We would
change the channel of the PHY context to channel 6 even if the BSS was
using that same PHY context.

Revamp that code and don't try to change a PHY context, it doesn't mean
much for the firmware anyway. Just remove it and allocate a new one.
This makes the logic easier to follow.

Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Gregory Greenman <gregory.greenman@intel.com>
Link: https://lore.kernel.org/r/20231011130030.4bc8b90d7be0.I1232dca3fe007362ec0ae0cf1d96217f2544e0d2@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>