target/ppc: moved stxv and lxv from legacy to decodtree

target/ppc: moved stxv and lxv from legacy to decodtree

Moved stxv and lxv implementation from the legacy system to
decodetree.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Luis Pires <luis.pires@eldorado.org.br>
Signed-off-by: Lucas Mateus Castro (alqotel) <lucas.castro@eldorado.org.br>
Signed-off-by: Matheus Ferst <matheus.ferst@eldorado.org.br>
Message-Id: <20211104123719.323713-13-matheus.ferst@eldorado.org.br>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>