target/ppc: Fix load endianness for lxvwsx/lxvdsx

target/ppc: Fix load endianness for lxvwsx/lxvdsx

TARGET_WORDS_BIGENDIAN may not match the machine endianness if that's a
runtime-configurable parameter.

Fixes: bcb0b7b1a1c05707304f80ca6f523d557816f85c
Fixes: afae37d98ae991c0792c867dbd9f32f988044318
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/212

Signed-off-by: Giuseppe Musacchio <thatlemon@gmail.com>
Message-Id: <20210518133020.58927-1-thatlemon@gmail.com>
Tested-by: Paul A. Clarke <pc@us.ibm.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
(cherry picked from commit 861f10fd528263a507476b8c4dda93a9588dfa5c)
Signed-off-by: Michael Roth <michael.roth@amd.com>