target/i386: fix byte swap issue with XMM register access

target/i386: fix byte swap issue with XMM register access

During the conversion to the gdb_get_reg128 helpers the high and low
parts of the XMM register where inadvertently swapped. This causes
reads of the register to report the incorrect value to gdb.

Resolves: https://gitlab.com/qemu-project/qemu/-/issues/971
Fixes: b7b8756a9c (target/i386: use gdb_get_reg helpers)
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Cc: qemu-stable@nongnu.org
Message-Id: <20220419091020.3008144-25-alex.bennee@linaro.org>