In demod_attach_stv0910(), the LNBH25 IC is being blindly attached and,
if the result is bad, blindly attached on another possible I2C address.
The LNBH25 uses it's set_voltage function to test for the IC and will
print an error to the kernel log on failure. Prevent this by probing
the possible I2C address and use this (and only this) to attach the
LNBH25 I2C driver. This also allows the stv0910 attach function to be
a bit cleaner.

Picked up from the upstream dddvb GIT and adapted for the LNBH25 driver
variant from the kernel tree.
Signed-off-by: Daniel Scheller <d.scheller@gmx.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>