qcacmn: Fix potential oob issue in wlan_parse_wapi_ie()

In function wlan_parse_wapi_ie(), len shows the remaining length
for ie content, it may cause oob issue when get uc_cipher_count
field from ie, need to add length check before get uc_cipher_count
field from ie.

Change-Id: Ie2d65284b2a172021d00f6385253368ec7603948
CRs-Fixed: 2832873