net: wireless: bcmdhd: Enable IPv6 RA filter feature

* We will block IPv6 Router Advertisement multicast packet
  in suspend mode to save power on device.

Bug: 11638281 Signed-off-by: Ecco Park <eccopark@broadcom.com>
Change-Id: I88199a08ff6d73923e87dfa77acd2299eb89e8f4