Change the simulator to use the generic timer_irq.c and serial_irq.c
code for (dummy) timer and io handling. This is just to make the code
a better example for other developers (most micro-controllers will use
the timer_irq.c and serial_irq.c code).
Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
Extract out common code from avr/serial.c, sam3x8e/serial.c, and
stm32f1/serial.c into a new generic/serial_irq.c file.
Signed-off-by: Kevin O'Connor <kevin@koconnor.net>