Add VSX Vector Move Instructions

This patch adds the vector move instructions:

  - xvabsdp - Vector Absolute Value Double-Precision
  - xvnabsdp - Vector Negative Absolute Value Double-Precision
  - xvnegdp - Vector Negate Double-Precision
  - xvcpsgndp - Vector Copy Sign Double-Precision
  - xvabssp - Vector Absolute Value Single-Precision
  - xvnabssp - Vector Negative Absolute Value Single-Precision
  - xvnegsp - Vector Negate Single-Precision
  - xvcpsgnsp - Vector Copy Sign Single-Precision

V3: Per Paolo Bonzini's suggestion, used a temporary for the
sign mask and andc.

Signed-off-by: Tom Musta <tommusta@gmail.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
