Starting a KVM guest on s390 fails immediately. This is because
"qemu --help" reports -no-acpi even for the s390(x) architecture but
-no-acpi isn't supported there.
Workaround is to remove QEMU_CAPS_NO_ACPI from the capability set
after the version/capability extraction.
Signed-off-by: NViktor Mihajlovski <mihajlov@linux.vnet.ibm.com>