wlan: Change the length of the extended capabilities IE

When the wpa_supplicant enables the FILS flag, when it issues the
connection command, it sets the Ext Caps length as 10.
But for prima, the function limUpdateExtCapIEtoStruct() returns
because the length is invalid, so it will skip the Ext Caps IE in
the assoc request frame.

Modify the extended capabilities IE length to 15.

Change-Id: I2dad7a0c77548e676674309bf64c9405c0dd9554
CRs-Fixed: 2349134