qemu: capabilities: Move setting of QEMU_CAPS_MACH_VIRT_GIC_VERSION to virQEMUCapsIni...

qemu: capabilities: Move setting of QEMU_CAPS_MACH_VIRT_GIC_VERSION to virQEMUCapsInitQMPBasicArch

Move it under AARCH 64, since it's a platform specific feature, thus it
will be removed from all other platforms.

Since virQEMUCapsInitQMPBasicArch is used in qemuxml2argv test to
initiate qemuCaps for tests with fake capabilities, all the tests gain
GIC support now.

Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Pavel Hrdina <phrdina@redhat.com>
Reviewed-by: Neal Gompa <ngompa13@gmail.com>
Reviewed-by: Pavel Hrdina <phrdina@redhat.com>