This patch enables the virtual networking over RPMsg communication
between Safety Island and the DomU guest of Primary Compute.

The remoteproc driver is changed to use the device memory region
because Xen does not support reserved memory passthrough. But
unaligned access to the device memory causes exception in the EL2. A
Xen patch is added to introduce 'xen,reg-normal-memory' tag. This
tag indicates that Xen needs to configure the device regions to
normal memory.

In the Linux kernel, virtio vring is forced to enable DMA operations
in the Xen domains. It causes incorrect DMA page mapping because DMA
is not used for armv8r64_remoteproc-based virtio RPMsg. Add a Linux
kernel patch to fix it by checking the device type before forcing
virtio device to enable DMA operations.

In the Xen device tree, two tags are added to remoteproc node. One
for device passthrough, another for indicating that the device region
is normal memory. In the Xen tool configuration, the I/O memory pages
are configured for the remoteproc device passthrough. The remoteproc
driver parses the 'reg' and 'reg-name' parameters to map the shared
memory regions in the guest.

The virtual networking in the DomU follows the configuration in the
baremetal linux case, which is defined in init-ifupdown-extras.inc.

As a testing application in the intermedium stage, the ipm_mhuv2
application is removed from Safety Island component.

Issue-Id: SCM-5480
Signed-off-by: Yanqin Wei <Yanqin.Wei@arm.com>
Change-Id: Ife07a16c2aa42671fb291189c66e4173c0e6ec39