This patch adds driver for tc90522 demodulator chips.
The chip contains 4 demod modules that run in parallel and are independently
controllable via separate I2C addresses.
Two of the modules are for ISDB-T and the rest for ISDB-S.
It is used in earthsoft pt3 cards.

Note that this driver does not init the chip,
because the initilization sequence / register setting is not disclosed.
Thus, the driver assumes that the chips are initilized externally
by its parent board driver before fe->ops->init() are called.
Earthsoft PT3 PCIe card, for example, contains the init sequence
in its private memory and provides a command to trigger the sequence.

Signed-off-by: Akihiro Tsukada <tskd08@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>