fsi: Create bus specific probe and remove functions

fsi: Create bus specific probe and remove functions

Introduce a bus specific probe and remove function. For now this only
allows to get rid of a cast of the generic device to an fsi device in
the drivers and changes the remove prototype to return void---a non-zero
return value is ignored anyhow.

The objective is to get rid of users of struct device callbacks
.probe(), .remove() and .shutdown() to eventually remove these.

Until all fsi drivers are converted this results in a runtime warning
about the drivers needing an update because there is a bus probe
function and a driver probe function.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
Acked-by: Eddie James <eajames@linux.ibm.com>
Link: https://patch.msgid.link/3b53adb75a5ae7894736d46cb6eb85f5ef36520e.1765279318.git.u.kleine-koenig@baylibre.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>