virtio: Enable virtio-scmi and IIO SCMI drivers.

virtio: Enable virtio-scmi and IIO SCMI drivers.

VIRTIO-SCMI device implements the Arm System Control and Management
Interface (SCMI) [1]. This VIRTIO device is part of "Virtual I/O Device
(VIRTIO) Version 1.2" specification [2].

The SCMI can be used for sensors, power state management, clock
management and performance management among other things.

Enable IIO-SCMI driver that works on top of VIRTIO-SCMI and supports
SCMI sensors.

[1]: https://developer.arm.com/Architectures/System%20Control%20and%20Management%20Interface
[2]: https://docs.oasis-open.org/virtio/virtio/v1.2/csd01/virtio-v1.2-csd01.html

Bug-AGL: SPEC-3865, SPEC-4365
Change-Id: Iaf2092d869d938d0b45029038d8eea36110d7e3e
Signed-off-by: Vasyl Vavrychuk <vasyl.vavrychuk@opensynergy.com>
Reviewed-on: https://gerrit.automotivelinux.org/gerrit/c/AGL/meta-agl/+/27473
Tested-by: Jenkins Job builder account
ci-image-build: Jenkins Job builder account
ci-image-boot-test: Jenkins Job builder account
Reviewed-by: Jan-Simon Moeller <jsmoeller@linuxfoundation.org>