The current/default behavior of set blacklist BSSID QCA vendor command
is a mandate to the driver - do not consider this BSSID for connect/roam
till reset.
There are use cases where this need not be a mandate and thus could
provide the flexibility for the driver to consider this BSSID if there
are no better ones. Such use cases can use this new flag attribute to
only hint the blacklist of a BSSID to the driver.
Signed-off-by: Jouni Malinen <jouni@codeaurora.org>