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/Makefile b/drivers/of/Makefile
index f232cc9..3631a5e 100644
--- a/drivers/of/Makefile
+++ b/drivers/of/Makefile
@@ -1,5 +1,6 @@
 obj-y = base.o
 obj-$(CONFIG_OF_FLATTREE) += fdt.o
+obj-$(CONFIG_OF_IRQ)    += irq.o
 obj-$(CONFIG_OF_DEVICE) += device.o platform.o
 obj-$(CONFIG_OF_GPIO)   += gpio.o
 obj-$(CONFIG_OF_I2C)	+= of_i2c.o