Add a VSX CPU feature.  Also add code to detect if VSX is available
from the device tree.
Signed-off-by: NMichael Neuling <mikey@neuling.org>
Signed-off-by: NJoel Schopp <jschopp@austin.ibm.com>
Signed-off-by: NPaul Mackerras <paulus@samba.org>