target/loongarch: Terminate vmstate subsections list

This list requires a NULL terminator.

Fixes: 16f5396cec23 ("target/loongarch: Add LSX data type VReg")
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20230510062405.127260-1-richard.henderson@linaro.org>
diff --git a/target/loongarch/machine.c b/target/loongarch/machine.c
index 7adc1bd..d8ac99c 100644
--- a/target/loongarch/machine.c
+++ b/target/loongarch/machine.c
@@ -163,5 +163,6 @@
     .subsections = (const VMStateDescription*[]) {
         &vmstate_fpu,
         &vmstate_lsx,
+        NULL
     }
 };