i386: Fixup last pblendw change.

Missed changing one predicate to AVX2.  Add parenthesis
to avoid bootstrap -Werror.

From-SVN: r179700

gcc/config/i386/predicates.md

@@ -1217,5 +1217,5 @@
 {
   HOST_WIDE_INT val = INTVAL (op);
   HOST_WIDE_INT low = val & 0xff;
-  return val == (low << 8) | low;
+  return val == ((low << 8) | low);
 })

gcc/config/i386/sse.md

@@ -9453,7 +9453,7 @@
 	  (match_operand:V16HI 2 "nonimmediate_operand" "xm")
 	  (match_operand:V16HI 1 "register_operand" "x")
 	  (match_operand:SI 3 "avx2_pblendw_operand" "n")))]
-  "TARGET_SSE4_1"
+  "TARGET_AVX2"
 {
   operands[3] = GEN_INT (INTVAL (operands[3]) & 0xff);
   return "vpblendw\t{%3, %2, %1, %0|%0, %1, %2, %3}";