ppc64 iseries: move some iSeries include files

These files are only referenced from within
arch/powerpc/platforms/iseries, so move them there.

Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>

arch/powerpc/platforms/iseries/irq.h

@@ -0,0 +1,8 @@
+#ifndef	_ISERIES_IRQ_H
+#define	_ISERIES_IRQ_H
+
+extern void iSeries_init_IRQ(void);
+extern int  iSeries_allocate_IRQ(HvBusNumber, HvSubBusNumber, HvAgentId);
+extern void iSeries_activate_IRQs(void);
+
+#endif /* _ISERIES_IRQ_H */