Only the Layerscape SoCs have interrupts on bus idle, which facilitate
sending events which complete slave bus transactions.

Add support for synthesizing missing events. If we see a master request,
or a newly addressed slave request, if the last event sent to the backend
was I2C_SLAVE_READ_REQUESTED, send the backend a I2C_SLAVE_READ_PROCESSED
followed by I2C_SLAVE_STOP. For all other events, send an I2C_SLAVE_STOP.
Signed-off-by: Kevin Paul Herbert <kph@platinasystems.com>
Tested-by: Oleksij Rempel <o.rempel@pengutronix.de>
Reviewed-by: Oleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: Wolfram Sang <wsa@kernel.org>