Add N3RegVShFrm to represent 3-Register Vector Shift Instructions, which do not

follow the N3RegFrm's operand order of D:Vd N:Vn M:Vm.  The operand order of
N3RegVShFrm is D:Vd M:Vm N:Vn (notice that M:Vm is the first src operand).

Add a parent class N3Vf which requires passing a Format argument and which the
N3V class is modified to inherit from.  N3V class represents the "normal"
3-Register NEON Instructions with N3RegFrm.

Also add a multiclass N3VSh_QHSD to represent clusters of NEON 3-Register Shift
Instructions and replace 8 invocations with it.

llvm-svn: 99655