On the zephyr port, hard IRQ handlers run with a separate stack on a
different thread, so each call to mp_irq_dispatch() and mp_irq_handler()
has to be wrapped with adjustments to the stack-limit checker.
Move these adjustments into the shared mp_irq_dispatch(), introducing
MICROPY_STACK_SIZE_HARD_IRQ which a port can define to non-zero if it
uses a separate stack for hard IRQ handlers. We only need wrap the hard
dispatch case. This should reduce binary size on zephyr without affecting
other ports.
Signed-off-by: Chris Webb <chris@arachsys.com>
