interrupt_controller: cavs: add support in ISR for SMP

The CAVS interrupt controller has different base addresses for
each CPU. When running under SMP, the driver needs to look at
the correct address for the CPU the ISR is running so interrupts
can be dispatched correctly. This adds a function to calculate
the correct base address. Note that each supported SoC may have
different offsets so per SoC config will need to added. Support
for intel_s1000 is added as an example.

Signed-off-by: Daniel Leung <daniel.leung@intel.com>