wip: vec_round_from_fp32 seem to be throwing rounding errors

Signed-off-by: Aaron Teo <aaron.teo1@ibm.com>

Author: taronaeo

ggml/src/ggml-cpu/ggml-cpu.c

@@ -3140,10 +3140,10 @@ void ggml_cpu_fp32_to_fp16(const float * x, ggml_fp16_t * y, int64_t n) {
 
 #if defined(__NNPA__)
     for (; i + 7 < n; i += 8) {
-        uint16_t tmp[8];
+        int16_t tmp[8];
         float32x4_t v_x1 = vec_xl(0, x + i + 0);
         float32x4_t v_x2 = vec_xl(0, x + i + 4);
-        uint16x8_t v_dlf16 = vec_round_from_fp32(v_x1, v_x2, 0);
+        int16x8_t v_dlf16 = vec_round_from_fp32(v_x1, v_x2, 0);
         vec_xst(v_dlf16, 0, tmp);
         raise(SIGINT);
     }