target/riscv: Remove floatX_maybe_silence_nan from conversions

This is now handled properly by the generic softfloat code.

Cc: Palmer Dabbelt <palmer@sifive.com>
Cc: Sagar Karandikar <sagark@eecs.berkeley.edu>
Cc: Bastian Koppelmann <kbastian@mail.uni-paderborn.de>
Reviewed-by: Michael Clark <mjc@sifive.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

target/riscv/fpu_helper.c

@@ -279,14 +279,12 @@ uint64_t helper_fmax_d(CPURISCVState *env, uint64_t frs1, uint64_t frs2)
 
 uint64_t helper_fcvt_s_d(CPURISCVState *env, uint64_t rs1)
 {
-    rs1 = float64_to_float32(rs1, &env->fp_status);
-    return float32_maybe_silence_nan(rs1, &env->fp_status);
+    return float64_to_float32(rs1, &env->fp_status);
 }
 
 uint64_t helper_fcvt_d_s(CPURISCVState *env, uint64_t rs1)
 {
-    rs1 = float32_to_float64(rs1, &env->fp_status);
-    return float64_maybe_silence_nan(rs1, &env->fp_status);
+    return float32_to_float64(rs1, &env->fp_status);
 }
 
 uint64_t helper_fsqrt_d(CPURISCVState *env, uint64_t frs1)