Add optional reassoc-to-same-BSS optimization

Add optional reassoc-to-same-BSS optimization

The new reassoc_same_bss_optim=1 configuration parameter can now be used
to request wpa_supplicant to bypass the unnecessary Authentication frame
exchange when reassociating back to the same BSS with which the device
is already associated. This functionality is disabled by default since
it may cause undesired interoperability issues with some APs.

Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>