generic: Move simulator/irq.h to new file generic/irq.h

Move the generic irq definitions into generic/irq.h and move the
simulator irq code into main.c.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

src/generic/irq.h

@@ -0,0 +1,11 @@
+#ifndef __GENERIC_IRQ_H
+#define __GENERIC_IRQ_H
+
+#include <stdint.h>
+
+void irq_disable(void);
+void irq_enable(void);
+uint8_t irq_save(void);
+void irq_restore(uint8_t flag);
+
+#endif // irq.h