wlan: Remove off-by-one write condition in sch_beacon_process

In the API, the driver inserts 0 after the SSID name, to mark the
end of the ssid, but if the SSID name is 32 characters which is
the max SSID length possible, the driver puts 0 at the 33rd
place of memory which is not the part of the SSID name, which
results in OOB write, or off-by-one write condition.

Fix is to remove the addition of 0 after ssid, as in every
case the driver prints the ssid, taking the ssid length
as the input, and in that case insertion of 0 will not serve
any purpose.

Change-Id: I1d58026ec9f48fe9d00bd2f50783c65899588978
CRs-Fixed: 2598900