spi: Export acpi_spi_find_controller_by_adev()

Export acpi_spi_find_controller_by_adev() so that ACPI glue code which
wants to dynamically create a spi_device using acpi_spi_device_alloc() or
spi_new_device() on a controller, to which the code does not already have
a reference, can find the controller.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20231014205314.59333-2-hdegoede@redhat.com


Signed-off-by: Mark Brown <broonie@kernel.org>