iwlwifi: mvm: fix scan condition iterator

Scan condition iterator assumes that an interface is associated if
phy_ctxt is assigned, but this isn't the sutuation in P2P device.
OTOH P2P device is never associated so we can simply ignore it.

Signed-off-by: David Spinadel <david.spinadel@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>