driver core: bus: constantify the bus_find_* functions

All of the bus find and iterator functions do not modify the struct
bus_type passed to them, so mark them as constant to enforce this rule.

Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Link: https://lore.kernel.org/r/20230208111330.439504-4-gregkh@linuxfoundation.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>