cache: Support cache maintenance for HiSilicon SoC Hydra Home Agent

cache: Support cache maintenance for HiSilicon SoC Hydra Home Agent

Hydra Home Agent is a device used to maintain cache coherency. Add support
for explicit cache maintenance operations using it. A system has multiple
of these agents. Whilst only one agent is responsible for a given cache
line, interleave means that for a range operation, responsibility for the
cache lines making up the range will typically be spread across multiple
instances.

Put this driver on a new Kconfig menu under drivers/cache. The short
description as memory hotplug like operations is intended to cover
the somewhat complex set of cases where this unit applies and differentiate
it clearly from typical non coherent DMA flows.

Co-developed-by: Yicong Yang <yangyicong@hisilicon.com>
Signed-off-by: Yicong Yang <yangyicong@hisilicon.com>
Signed-off-by: Yushan Wang <wangyushan12@huawei.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>