hw/armv7m_nvic: Correctly register GIC region when setting up NVIC

hw/armv7m_nvic: Correctly register GIC region when setting up NVIC

When setting up the NVIC memory regions the memory range
0x100..0xcff is aliased to an IO memory region that belongs
to the ARM GIC.  This aliased region should be added to the
NVIC memory container, but the actual GIC IO memory region
was being added instead.  This mixup was causing the wrong
IO memory access functions to be called when accessing parts
of the NVIC memory.

Signed-off-by: Meador Inge <meadori@codesourcery.com>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>