target-s390: Fix STURA

We were storing 16 bits instead of 32.

Signed-off-by: Richard Henderson <rth@twiddle.net>
diff --git a/target-s390x/mem_helper.c b/target-s390x/mem_helper.c
index 5a55de8..4736b7b 100644
--- a/target-s390x/mem_helper.c
+++ b/target-s390x/mem_helper.c
@@ -1039,7 +1039,7 @@
 {
     CPUState *cs = CPU(s390_env_get_cpu(env));
 
-    stw_phys(cs->as, get_address(env, 0, 0, addr), (uint32_t)v1);
+    stl_phys(cs->as, get_address(env, 0, 0, addr), (uint32_t)v1);
 }
 
 /* load real address */