V4L/DVB (11398): Support for Legend Silicon LGS8913/LGS8GL5/LGS8GXX China DMB-TH digital demodulator

This patch contains the unified driver for Legend Silicon LGS8913 and
LGS8GL5. It should replace lgs8gl5.c in media/dvb/frontends in the future.
Signed-off-by: David T.L. Wong <davidtlwong@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>