greybus: move is_gb_* functions out of greybus.h

The functions below are only used within the context of
drivers/greybus/core.c, so move them all into core and drop their 'inline'
specifiers:

is_gb_host_device(), is_gb_module(), is_gb_interface(), is_gb_control(),
is_gb_bundle() and is_gb_svc().

Suggested-by: Alex Elder <elder@ieee.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: "Ricardo B. Marliere" <ricardo@marliere.net>
Reviewed-by: Alex Elder <elder@linaro.org>
Link: https://lore.kernel.org/r/20240226-device_cleanup-greybus2-v1-1-5f7d1161e684@marliere.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

greybus: make greybus_bus_type const

Now that the driver core can properly handle constant struct bus_type,
move the greybus_bus_type variable to be a constant structure as well,
placing it into read-only memory which can not be modified at runtime.

Cc: Alex Elder <elder@kernel.org>
Cc: greybus-dev@lists.linaro.org
Reviewed-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/2024010517-handgun-scoreless-05e7@gregkh
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

driver core: make struct bus_type.uevent() take a const *

The uevent() callback in struct bus_type should not be modifying the
device that is passed into it, so mark it as a const * and propagate the
function signature changes out into all relevant subsystems that use
this callback.

Acked-by: Rafael J. Wysocki <rafael@kernel.org>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20230111113018.459199-16-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

staging: greybus: move the greybus core to drivers/greybus

The Greybus core code has been stable for a long time, and has been
shipping for many years in millions of phones. With the advent of a
recent Google Summer of Code project, and a number of new devices in the
works from various companies, it is time to get the core greybus code
out of staging as it really is going to be with us for a while.

Cc: Johan Hovold <johan@kernel.org>
Cc: linux-kernel@vger.kernel.org
Cc: greybus-dev@lists.linaro.org
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Alex Elder <elder@kernel.org>
Link: https://lore.kernel.org/r/20190825055429.18547-9-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>