hwmon: Add driver for Astera Labs PT5161L retimer

This driver implements support for temperature monitoring of Astera Labs
PT5161L series PCIe retimer chips.

This driver implementation originates from the CSDK available at
Link: https://github.com/facebook/openbmc/tree/helium/common/recipes-lib/retimer-v2.14
The communication protocol utilized is based on the I2C/SMBus standard.

Signed-off-by: Cosmo Chou <chou.cosmo@gmail.com>
Link: https://lore.kernel.org/r/20240206125420.3884300-2-chou.cosmo@gmail.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>