V4L/DVB (9364): adding sharp s921 ISDB-T driver

s921_module.c:
    wrapper for the dvb frontend interface
    s921_core.c:
    core s921 1seg ISDB-T driver, everything is set to auto as much as possible
    in order to not require certain parameters which currently cannot be passed
    to the ISDB-T chip.

    ISDB-T support can be tested using dvbscan, dvbstream/snoop and mplayer
    Tested 1seg H264/aac stream with this driver using a custom linux
ISDB-T player

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>