target-or32: Add system instructions

Add OpenRISC system instructions.

Signed-off-by: Jia Liu <proljc@gmail.com>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
diff --git a/target-openrisc/Makefile.objs b/target-openrisc/Makefile.objs
index 926fc2f..44dc539 100644
--- a/target-openrisc/Makefile.objs
+++ b/target-openrisc/Makefile.objs
@@ -1,4 +1,4 @@
 obj-$(CONFIG_SOFTMMU) += machine.o
 obj-y += cpu.o exception.o interrupt.o mmu.o translate.o
 obj-y += exception_helper.o fpu_helper.o int_helper.o \
-         interrupt_helper.o mmu_helper.o
+         interrupt_helper.o mmu_helper.o sys_helper.o