m68k: Switch to asm-generic/hardirq.h

Classic m68k with MMU was converted to generic hardirqs a long time ago,
and there are no longer include dependency issues preventing the direct
use of asm-generic/hardirq.h.

Signed-off-by: Geert Uytterhoeven <[email protected]>
Acked-by: Greg Ungerer <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

Author: geertu

arch/m68k/include/asm/Kbuild

@@ -8,6 +8,7 @@ generic-y += emergency-restart.h
 generic-y += exec.h
 generic-y += extable.h
 generic-y += futex.h
+generic-y += hardirq.h
 generic-y += hw_irq.h
 generic-y += irq_regs.h
 generic-y += irq_work.h