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>

arch/mips/include/uapi/asm/inst.h

@@ -305,6 +305,7 @@ enum mm_32axf_minor_op {
 	mm_jalrshb_op = 0x17c,
 	mm_sync_op = 0x1ad,
 	mm_syscall_op = 0x22d,
+	mm_wait_op = 0x24d,
 	mm_eret_op = 0x3cd,
 };