target-arm: Update PC before calling gen_helper_check_breakpoints()

PC should be updated in the CPU state before calling check_breakpoints()
helper. Otherwise, the helper would not see the correct PC in the CPU
state if it is not at the start of a TB.

Signed-off-by: Sergey Fedorov <serge.fdrv@gmail.com>
Message-id: 1447176222-16401-1-git-send-email-serge.fdrv@gmail.com
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
