Add dynamic layer for raspberrypi and rcar-gen3

Add dynamic layer for raspberrypi and rcar-gen3

Updates [v2]:
It backports the virtio-sound module for rcar-gen3 and enables
virtio-sound, virtio-can, virtio-input, virtio-console,
virtio-loopback for both cases.

Updates [v1]:
Add linux-renesas kernel configuration

Specifically this commit creates a new directory 'linux-renesas'
for configuring the required modules to be loaded by that kernel.
It is also backports the virtio-sound module and enables
virtio-sound, virtio-can, virtio-input, virtio-console and
virtio-loopback.

Virtio-sound module sources:
Source: https://lore.kernel.org/alsa-devel/20210302164709.3142702-1-anton.yakovlev@opensynergy.com

Bug-AGL: SPEC-4966

Change-Id: Ie143e690695a526958e07a66ba481887b2e4a248
Signed-off-by: Timos Ampelikiotis <t.ampelikiotis@virtualopensystems.com>