target/m68k: Always return a temporary from gen_lea_mode

target/m68k: Always return a temporary from gen_lea_mode

Returning a raw areg does not preserve the value if the areg
is subsequently modified.  Fixes, e.g. "jsr (sp)", where the
return address is pushed before the branch.

Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2483
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20240813000737.228470-1-richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
(cherry picked from commit 352cc9f300d83ea48b8154bfd2ff985fece887d0)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>