media: media/dvb: earth-pt3: use the new i2c binding helper

This patch slightly simplifies the binding code by introducing commit
8f569c0b ("media: dvb-core: add helper functions for I2C binding").

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