MAINTAINERS: Add OpenRISC pic maintainer

The OpenRISC team is the maintainer of the irqchip or1k-pic driver under
drivers/irqchip.

Signed-off-by: Stafford Horne <shorne@gmail.com>
diff --git a/MAINTAINERS b/MAINTAINERS
index d85c089..543d9fda 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -10032,6 +10032,7 @@
 W:	http://openrisc.io
 S:	Maintained
 F:	arch/openrisc/
+F:	drivers/irqchip/irq-or1k-*
 
 OPENVSWITCH
 M:	Pravin Shelar <pshelar@nicira.com>