qcacmn: SSID with zero or space should be NULL ssid

Last frame received in scan before the connect is
beacon with NULL ssid with non zero length and ssid
is sent as NULL to supplicant after association. This
will result in supplicant to trigger disconnect
casuing delay in reconnection.

Fix is to consider ssid with zeros or spaces as null
ssid.

Change-Id: If96776ae85926948d714e975c3e9b4011e8a20b3
CRs-Fixed: 2330485
3 files changed