Currently, reinstallations of the PTK are prevented by (1) assuring the same TPTK is only set once as the PTK, and (2) that one particular PTK is only installed once. This patch makes it more explicit that point (1) is required to prevent key reinstallations. At the same time, this patch hardens wpa_supplicant such that future changes do not accidentally break this property. Signed-off-by: Mathy V