target-ppc: add vmul10[u,eu,cu,ecu]q instructions

vmul10uq  : Vector Multiply-by-10 Unsigned Quadword VX-form
vmul10euq : Vector Multiply-by-10 Extended Unsigned Quadword VX-form
vmul10cuq : Vector Multiply-by-10 & write Carry Unsigned Quadword VX-form
vmul10ecuq: Vector Multiply-by-10 Extended & write Carry Unsigned Quadword VX-form

Signed-off-by: Vasant Hegde <hegdevasant@linux.vnet.ibm.com>
[ Add GEN_VXFORM_DUAL_EXT with invalid bit mask ]
Signed-off-by: Nikunj A Dadhania <nikunj@linux.vnet.ibm.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
