qemux86: disable paravirt guest in linux 3.4, causes test failures

The shutdown sanity test that we previously saw on qemux86-64 in 2.6.37 have
started to re-appear reproducably on qemux86 in 3.4 in the Danny series.  Until
this can be root-caused and fixed in the kernel, disable paravirtualisation
across all kernels and all qemu machines.

[ YOCTO #4196 ]

Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>