qcacmn: Add wmi service bit

Add wmi service bit: wmi_service_sta_plus_sta_support.

When this wmi service bit is set, firmware shall support simultaneous
connections on multiple STA interfaces.

If firmware doesn't set this service bit and if the host driver
doesn't check this bit before second STA connection, then firmware
shall reject connection by returning failure in VDEV_START_RESP_EVENTID.

Change-Id: I9e20911af5372b651586f25d9f13e4364c672435
CRs-Fixed: 2427202