media: lgdt3306a: Announce successful creation

The driver is near silent, this adds a simple announcement at the
end of probe after the chip has been detected and upgrades a debug
message to error if probe has failed.

Signed-off-by: Brad Love <brad@nextdimension.cc>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>