Input: Add IBM Operation Panel driver

Input: Add IBM Operation Panel driver

Add a driver to get the button events from the panel and provide
them to userspace with the input subsystem. The panel is
connected with I2C and controls the bus, so the driver registers
as an I2C slave device.

Signed-off-by: Eddie James <eajames@linux.ibm.com>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com> # I2C slave parts
Link: https://lore.kernel.org/r/20220809204147.238132-3-eajames@linux.ibm.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>