xen/arm: Add support for GICv3 for domU

The vGIC will emulate the same version as the hardware. The toolstack has
to retrieve the version of the vGIC in order to be able to create the
corresponding device tree node.

A new DOMCTL has been introduced for ARM to configure the domain. For now
it only allow the toolstack to retrieve the version of vGIC.
This DOMCTL will be extend later to let the user choose the version of the
emulated GIC.

Signed-off-by: Vijaya Kumar K <Vijaya.Kumar@caviumnetworks.com>
Signed-off-by: Julien Grall <julien.grall@linaro.org>
Cc: Ian Jackson <ian.jackson@eu.citrix.com>
Cc: Jan Beulich <jbeulich@suse.com>
Acked-by: Daniel De Graaf <dgdegra@tycho.nsa.gov>
Cc: Wei Liu <wei.liu2@citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
pvgrub: ignore NUL

When using pvgrub in graphical mode with vnc, the grub timeout doesn't
work: the countdown doesn't even start. With a serial terminal the
problem doesn't occur and the countdown works as expected.

It turns out that the problem is that when using a graphical terminal,
checkkey () returns 0 instead of -1 when there is no activity on the
mouse or keyboard. As a consequence grub thinks that the user typed
something and interrupts the count down.

To fix the issue simply ignore keystrokes returning 0, that is the NUL
character anyway. Add a patch to grub.patches to do that.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Tested-by: Steven Haigh <netwiz@crc.id.au>
Acked-by: Samuel Thibault <samuel.thibault@ens-lyon.org>