wl18xx: add version 3 of the wl18xx firmware

There are new APIs in the latest version of the wl18xx firmware. Add
the new firmware with a new filename (wl18xx-fw-3.bin), which
corresponds to firmware revision 8.8.0.0.13.
Signed-off-by: Arik Nemtsov <arik@wizery.com>

WHENCE

@@ -1835,6 +1835,8 @@ File: ti-connectivity/wl18xx-fw.bin
 Version: 8.2.0.0.100
 File: ti-connectivity/wl18xx-fw-2.bin
 Version: 8.5.0.0.55
+File: ti-connectivity/wl18xx-fw-3.bin
+Version: 8.8.0.0.13
 File: ti-connectivity/wl18xx-conf.bin
 Version: 6/5