Import ARCv2 architecture patch

[stephanosio]

Import the ARCv2 architecture patch (currently based on QEMU 4.2) into the zephyr-qemu repository.

https://github.com/zephyrproject-rtos/sdk-ng/blob/master/meta-zephyr-sdk/recipes-devtools/qemu/files/0006-Add-support-for-ARCv2-architecture.patch

Merged into sdk-ng in zephyrproject-rtos/sdk-ng#208

Since the zephyr-qemu repository is based on QEMU 5.0 at the time of writing, the patch will need to be converted to work with it.

[stephanosio]

@abrodkin Do you have any estimate on when you will have the QEMU 5.0 port of this patch?

[abrodkin]

@stephanosio in fact we do have re-based on top of v5.0 version so if needed I may post those changes somewhere. Just let me know in which form you prefer to get it and when.

[stephanosio]

@stephanosio in fact we do have re-based on top of v5.0 version so if needed I may post those changes somewhere. Just let me know in which form you prefer to get it and when.

@abrodkin That's great. Git .patch format would be nice, so I can import your commits here and in the sdk-ng QEMU 5.0 PR.

[abrodkin]

There seems to be no way to create a pull-request if I didn't clone from your repo, so you may just cherry-pick this one - abrodkin/qemu@d2fb10a. It's based on your current master.
Tried to run both qemu_arc_em & qemu_arc_hs and it worked as good as 4.2.