[media] drxk: pass drxk priv struct instead of I2C adapter to i2c calls

As it will be using the unlocked version of i2c_transfer during
firmware loads, make sure that the priv state routine will be
used on all I2C calls, in preparation for the next patch that
will implement an exclusive lock mode to be used during firmware
load, at drxk_init.

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>