powerpc: Remove powermac/pic.h

Its unused, and of the three declarations, one is duplicated in pmac.h,
the second is static and the third is renamed and static.
Signed-off-by: Milton Miller <miltonm@bga.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/platforms/powermac/pic.h

-#ifndef __PPC_PLATFORMS_PMAC_PIC_H
-#define __PPC_PLATFORMS_PMAC_PIC_H
-
-#include <linux/irq.h>
-
-extern struct irq_chip pmac_pic;
-
-extern void pmac_pic_init(void);
-extern int pmac_get_irq(void);
-
-#endif /* __PPC_PLATFORMS_PMAC_PIC_H */