iommu/exynos: Add support for SYSMMU controller with bogus version reg

SYSMMU on some SoCs reports bogus values in VERSION register. Force
hardware version to 1.0 for such controllers. This patch also moves reading
version register to driver's probe() function.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>