of/irq: Move irq_of_parse_and_map() to common code

Merge common code between PowerPC and Microblaze.  SPARC implements
irq_of_parse_and_map(), but the implementation is different, so it
does not use this code.

Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Michal Simek <monstr@monstr.eu>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Jeremy Kerr <jeremy.kerr@canonical.com>

diff --git a/drivers/of/of_spi.c b/drivers/of/of_spi.c
index 5fed7e3..d504f1d 100644
--- a/drivers/of/of_spi.c
+++ b/drivers/of/of_spi.c
@@ -9,6 +9,7 @@
 #include <linux/of.h>
 #include <linux/device.h>
 #include <linux/spi/spi.h>
+#include <linux/of_irq.h>
 #include <linux/of_spi.h>
 
 /**