P2P: Fix group idle timer cancellation on group removal
The wpas_p2p_group_idle_timeout was getting cancelled in the beginning
of wpas_p2p_group_delete(). However, in the case of P2P client role,
this function called wpa_supplicant_deauthenticate() next and that ended
up changing state to WPA_DISCONNECTED which resulted in
wpas_p2p_notif_disconnected() rescheduling the timeout. This left the
unexpected timeout behind after the group was removed. If another group
operation was started within P2P_MAX_CLIENT_IDLE (10) seconds, that
timeout could end up terminating the group while it was still being set
up.
Fix this by reordering wpas_p2p_group_delete() to cancel the group idle
timeout only after having called wpa_supplicant_deauthenticate(). The
group idle timeout is still rescheduled, but it gets removed immediately
afterwards when the actual group information is being cleared.