armv7m: Don't assume the NVIC's CPU is CPU 0

armv7m: Don't assume the NVIC's CPU is CPU 0

Currently the ARMv7M NVIC object's realize method assumes that the
CPU the NVIC is attached to is CPU 0, because it thinks there can
only ever be one CPU in the system. To allow a dual-Cortex-M33
setup we need to remove this assumption; instead the armv7m
wrapper object tells the NVIC its CPU, in the same way that it
already tells the CPU what the NVIC is.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20190121185118.18550-2-peter.maydell@linaro.org