target/ppc: implement xs[n]maddqp[o]/xs[n]msubqp[o]

Implement the following PowerISA v3.0 instuctions:
xsmaddqp[o]: VSX Scalar Multiply-Add Quad-Precision [using round to Odd]
xsmsubqp[o]: VSX Scalar Multiply-Subtract Quad-Precision [using round
             to Odd]
xsnmaddqp[o]: VSX Scalar Negative Multiply-Add Quad-Precision [using
              round to Odd]
xsnmsubqp[o]: VSX Scalar Negative Multiply-Subtract Quad-Precision
              [using round to Odd]

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Matheus Ferst <matheus.ferst@eldorado.org.br>
Message-Id: <20220225210936.1749575-38-matheus.ferst@eldorado.org.br>
Signed-off-by: Cédric Le Goater <clg@kaod.org>