powerpc/powernv: Add PIO accessors for Power8 LPC bus

This uses the hooks provided by CONFIG_PPC_INDIRECT_PIO to
implement a set of hooks for IO port access to use the LPC
bus via OPAL calls for the first 64K of IO space

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/kernel/io.c

@@ -25,6 +25,9 @@
 #include <asm/firmware.h>
 #include <asm/bug.h>
 
+/* See definition in io.h */
+bool isa_io_special;
+
 void _insb(const volatile u8 __iomem *port, void *buf, long count)
 {
 	u8 *tbuf = buf;