target/s390x: Use user_or_likely in do_access_memset

Eliminate the ifdef by using a predicate that is
always true with CONFIG_USER_ONLY.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
diff --git a/target/s390x/tcg/mem_helper.c b/target/s390x/tcg/mem_helper.c
index 6cdbc34..5311a15 100644
--- a/target/s390x/tcg/mem_helper.c
+++ b/target/s390x/tcg/mem_helper.c
@@ -225,10 +225,7 @@
                              uint8_t byte, uint16_t size, int mmu_idx,
                              uintptr_t ra)
 {
-#ifdef CONFIG_USER_ONLY
-    memset(haddr, byte, size);
-#else
-    if (likely(haddr)) {
+    if (user_or_likely(haddr)) {
         memset(haddr, byte, size);
     } else {
         MemOpIdx oi = make_memop_idx(MO_UB, mmu_idx);
@@ -236,7 +233,6 @@
             cpu_stb_mmu(env, vaddr + i, byte, oi, ra);
         }
     }
-#endif
 }
 
 static void access_memset(CPUS390XState *env, S390Access *desta,