[media] si2157: Add support for Si2146-A10

[media] si2157: Add support for Si2146-A10

The Silicon Labs Si2146 tuner seems to work with the same driver as the Si2157,
but there a few exceptions. The powerup command seems to be quite a bit
different. In addition there's a property 0207 that requires a different value.
Thus another entry is created in the si2157_id table to support also si2146 in
this driver.

The datasheet is available on manufacturer's website:
http://www.silabs.com/support%20documents/technicaldocs/Si2146-short.pdf

Signed-off-by: Olli Salonen <olli.salonen@iki.fi>
Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>