Avoid reconnection on ENABLE_NETWORK if already connected

Avoid reconnection on ENABLE_NETWORK if already connected

This was already the case for most command sequences, but it was
possible for wpa_s->reassociate to be set to 1 when CTRL-RSP-* commands
were used to set identity, password, or passphrase for EAP
authentication. In such cases, ENABLE_NETWORK issued after the
connection was completed could result in a new connection attempt
(likely reconnection back to the same BSS).

Fix this by checking whether an actual connection is already present
even if wpa_s->reassociate is set when processing the ENABLE_NETWORK
command.

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