x86: add missing "prefix" attribute to VF{,C}MULC

gcc/

	* config/i386/sse.md
	(<avx512>_<complexopname>_<mode><maskc_name><round_name>): Add
	"prefix" attribute.
	(avx512fp16_<complexopname>sh_v8hf<mask_scalarc_name><round_scalarcz_name>):
	Likewise.

gcc/config/i386/sse.md

@@ -6790,6 +6790,7 @@
   return "v<complexopname><ssemodesuffix>\t{<round_maskc_op3>%2, %1, %0<maskc_operand3>|%0<maskc_operand3>, %1, %2<round_maskc_op3>}";
 }
   [(set_attr "type" "ssemul")
+   (set_attr "prefix" "evex")
    (set_attr "mode" "<MODE>")])
 (define_expand "avx512fp16_fmaddcsh_v8hf_maskz<round_expand_name>"
@@ -6993,6 +6994,7 @@
   return "v<complexopname>sh\t{<round_scalarc_mask_op3>%2, %1, %0<mask_scalarc_operand3>|%0<mask_scalarc_operand3>, %1, %2<round_scalarc_mask_op3>}";
 }
   [(set_attr "type" "ssemul")
+   (set_attr "prefix" "evex")
    (set_attr "mode" "V8HF")])
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;