iommu: iova: Move iova cache management to the iova library

This is necessary to separate intel-iommu from the iova library.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

diff --cc drivers/iommu/intel-iommu.c
Simple merge

diff --cc drivers/iommu/iova.c
Simple merge

diff --cc include/linux/iova.h
Simple merge