iommu: Move sg_table wrapper out of CONFIG_IOMMU_SUPPORT

Move the recently added sg_table wrapper out of CONFIG_IOMMU_SUPPORT to
let the client code copile also when IOMMU support is disabled.

Fixes: 48530d9f ("iommu: add generic helper for mapping sgtable objects")
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Link: https://lore.kernel.org/r/20200630081756.18526-1-m.szyprowski@samsung.com


Signed-off-by: Joerg Roedel <jroedel@suse.de>