ARM: EXYNOS: Fixup debug macros for big-endian

The exynos low-level debug macros need to be fixed if the system is being
built big endian. Add the necessary endian swaps for accessing the registers
to get output working again

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