platform/x86: serial-multi-instantiate: Reorganize I2C functions

Reorganize I2C functions to accommodate SPI support
Split the probe and factor out parts of the code
that will be used in the SPI support
Also switched from strlcpy() to strscpy()

Signed-off-by: Lucas Tanure <tanureal@opensource.cirrus.com>
Signed-off-by: Stefan Binding <sbinding@opensource.cirrus.com>
Link: https://lore.kernel.org/r/20220121172431.6876-7-sbinding@opensource.cirrus.com


Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>