regmap: kunit: Use a KUnit action to call regmap_exit()

Registert a KUnit action handler to call regmap_exit() when a test
terminates. This ensures that regmap_exit() will be called if a test
function returns early or aborts.

Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
Link: https://msgid.link/r/20240408144600.230848-9-rf@opensource.cirrus.com


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