target/arm: Define arm_cpu_do_unaligned_access for user-only

target/arm: Define arm_cpu_do_unaligned_access for user-only

Use the same code as system mode, so that we generate the same
exception + syndrome for the unaligned access.

For the moment, if MTE is enabled so that this path is reachable,
this would generate a SIGSEGV in the user-only cpu_loop.  Decoding
the syndrome to produce the proper SIGBUS will be done later.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20200626033144.790098-15-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>