fsi: Add IBM I2C Responder virtual FSI master

The I2C Responder (I2CR) is an I2C device that translates I2C commands
to CFAM or SCOM operations, effectively implementing an FSI master and
bus.

Signed-off-by: Eddie James <eajames@linux.ibm.com>
Link: https://lore.kernel.org/r/20230612195657.245125-14-eajames@linux.ibm.com


Signed-off-by: Joel Stanley <joel@jms.id.au>