bcmdhd: allow only unicast packets when screen is off

It seems HTC uses an ioctl instead of the packet filter to block broadcast a
    multicast packets but this does not work with the latest firmware.

    Bring back dhd_set_packet_filter.

Adapted to msm8660 from original commit by paulb-nl

Change-Id: I381fafaea954ad9e2dfe7d964231895589efeb43