target/arm: Replace offset with pc in gen_exception_insn

target/arm: Replace offset with pc in gen_exception_insn

The offset is variable depending on the instruction set, whereas
we have stored values for the current pc and the next pc.  Passing
in the actual value is clearer in intent.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-id: 20190807045335.1361-8-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>