dbus: Make P2P group properties accessible individually

dbus: Make P2P group properties accessible individually

Group properties are now accessible individually. The function to retrieve
the dictionary containing the group properties is removed in favor of the
individual functions. The group member properties are removed as well as
they erroneously retrieved the group properties via the old function.

Signed-hostap: Todd Previte <toddx.a.previte@intel.com>
Signed-hostap: Angie Chinchilla <angie.v.chinchilla@intel.com>
intended-for: hostap-1