MIPS: inst.h: define microMIPS wait op

The opcode for the wait instruction within POOL32AXf was missing. This
patch adds it for use by a subsequent patch.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
diff --git a/arch/mips/include/uapi/asm/inst.h b/arch/mips/include/uapi/asm/inst.h
index 89e9155..e6e7fe3 100644
--- a/arch/mips/include/uapi/asm/inst.h
+++ b/arch/mips/include/uapi/asm/inst.h
@@ -305,6 +305,7 @@
 	mm_jalrshb_op = 0x17c,
 	mm_sync_op = 0x1ad,
 	mm_syscall_op = 0x22d,
+	mm_wait_op = 0x24d,
 	mm_eret_op = 0x3cd,
 };