arcv: correct mode for widening XARCV instructions

Author: MichielDerhaeg

gcc/config/riscv/arcv-vector.md

@@ -2198,7 +2198,7 @@
   "TARGET_XARCVVSAD"
   "arcv.vwsad.v%o4\t%0,%3,%4%p1"
   [(set_attr "type" "viwmuladd")
-   (set_attr "mode" "<MODE>")])
+   (set_attr "mode" "<V_DOUBLE_TRUNC>")])
 
 (define_insn "@pred_widen_arcv_vwsadu<mode>"
   [(set (match_operand:VWEXTI 0 "register_operand" "=vd, vd, vr, vr, vd, vd, vr, vr, vd, vd, vr, vr")
@@ -2221,7 +2221,7 @@
   "TARGET_XARCVVSAD"
   "arcv.vwsadu.v%o4\t%0,%3,%4%p1"
   [(set_attr "type" "viwmuladd")
-   (set_attr "mode" "<MODE>")])
+   (set_attr "mode" "<V_DOUBLE_TRUNC>")])
 
 (define_insn "@pred_quad_widen_arcv_vqmxm4<mode>"
   [(set (match_operand:VQEXTI 0 "register_operand" "=vd, vd, vr, vr, vd, vd, vr, vr, vd, vd, vr, vr")