target/arm: Fix handling of LDAPR/STLR with negative offset

target/arm: Fix handling of LDAPR/STLR with negative offset

When we converted the LDAPR/STLR instructions to decodetree we
accidentally introduced a regression where the offset is negative.
The 9-bit immediate field is signed, and the old hand decoder
correctly used sextract32() to get it out of the insn word,
but the ldapr_stlr_i pattern in the decode file used "imm:9"
instead of "imm:s9", so it treated the field as unsigned.

Fix the pattern to treat the field as a signed immediate.

Cc: qemu-stable@nongnu.org
Fixes: 2521b6073b7 ("target/arm: Convert LDAPR/STLR (imm) to decodetree")
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2419
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20240709134504.3500007-2-peter.maydell@linaro.org