soc: samsung: pmu: Use of_device_get_match_data helper

Replace custom code with generic helper to retrieve driver data.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: Tomasz Figa <tomasz.figa@gmail.com>
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>