spi: s3c64xx: clean up runtime PM if driver registration fails

Fix missing runtime PM cleanup if driver registration fails.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Reviewed-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Signed-off-by: Mark Brown <broonie@kernel.org>