Add DVB SEC frontend driver for STM LNBH25PQR chip.

[mchehab@osg.samsung.com: fix merge conflict:
 fe_sec_voltage_t should not be used in kernelspace anymore.
 instead, it should use enum fe_sec_voltage]
Signed-off-by: NKozlov Sergey <serjk@netup.ru>
Signed-off-by: NMauro Carvalho Chehab <mchehab@osg.samsung.com>