target/ppc: fix vbpermd in big endian hosts

target/ppc: fix vbpermd in big endian hosts

The extract64 arguments are not endian dependent as they are only used
for bitwise operations. The current behavior in little-endian hosts is
correct; since the indexes in VRB are in PowerISA-ordering, we should
always invert the value before calling extract64. Also, using the VsrD
macro, we can have a single EXTRACT_BIT definition for big and
little-endian with the correct behavior.

Signed-off-by: Matheus Ferst <matheus.ferst@eldorado.org.br>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20220601125355.1266165-1-matheus.ferst@eldorado.org.br>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>