ARM: SAMSUNG: Fixup usage of __raw IO in PM

Fix the use of __raw accesors in pm-common.c to use the _relaxed
variants to deal with any issues due to endian related fetches.

Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>