i3c: remove i2c board info from i2c_dev_desc

I2C board info is only required during adapter setup so there is no
requirement to keeping a pointer to it once running.  To support dynamic
device addition we can't rely on board info - user-space creation
through sysfs won't have a boardinfo.

Cc: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Jamie Iles <quic_jiles@quicinc.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20220117174816.1963463-2-quic_jiles@quicinc.com