xtensa: fix build fail on undefined ack_bad_irq

Commit e520c410854bab763be24e0fce7ba89dc252efee

"xtensa: convert to asm-generic/hardirq.h"

converted over to using the asm-generic parts, but it also added the sentinel

	#define ack_bad_irq ack_bad_irq

which tells asm-generic to _not_ use the common ack_bad_irq.

Since e520c41 deleted the duplicated code from the arch specific file, we _do_ want the asm-generic one in scope. So delete the trigger define above which hides it. In doing so we'll realize that we've got to delete the almost-duplicate prototype as well to avoid "static declaration ... follows non-static".

index 26664ce..91695a1 100644
@@ -11,9 +11,6 @@
 #ifndef _XTENSA_HARDIRQ_H
 #define _XTENSA_HARDIRQ_H
 
-void ack_bad_irq(unsigned int irq);
-#define ack_bad_irq ack_bad_irq
-
 #include <asm-generic/hardirq.h>
 
 #endif	/* _XTENSA_HARDIRQ_H */

1.7.9.1