driver: sync I-cache, D-cache and memory

driver: sync I-cache, D-cache and memory

Syncronize I-cache with D-cache after loading the hypervisor
image or a cell image. This must be done in arm64 according to
ARMv8 ARM spec. See page 1712, D3.4.6 "Non-cacheable accesses
and instruction caches".

This patch fixes coherency problems observed on real HW targets.
On x86 this operation is a NOP.

Signed-off-by: Dmitry Voytik <dmitry.voytik@huawei.com>
Signed-off-by: Antonios Motakis <antonios.motakis@huawei.com>
[antonios.motakis@huawei.com: edited comments]

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>