target/arm: Fix offset for LD1R instructions

target/arm: Fix offset for LD1R instructions

The immediate should be scaled by the size of the memory reference,
not the size of the elements into which it is loaded.

Cc: qemu-stable@nongnu.org (3.0.1)
Reported-by: Laurent Desnogues <laurent.desnogues@gmail.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Tested-by: Laurent Desnogues <laurent.desnogues@gmail.com>
Reviewed-by: Laurent Desnogues <laurent.desnogues@gmail.com>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
(cherry picked from commit d0e372b0298f897993f831dbff7ad4f1c70f138e)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>