always use float as intermediate format

Author: JohannesGaessler

ggml/src/ggml-cuda/convert.cu

@@ -579,13 +579,7 @@ static __global__ void convert_unary(const void * __restrict__ vx, dst_t * __res
 
     const src_t * x = (const src_t *) vx;
 
-    if constexpr (std::is_same_v<src_t, nv_bfloat16>) {
-        y[i] = __bfloat162float(x[i]);
-    } else if constexpr (std::is_same_v<dst_t, nv_bfloat16> && std::is_same_v<src_t, half>) {
-        y[i] = (float)x[i];
-    } else {
-        y[i] = x[i];
-    }
+    y[i] = float(x[i]);
 }
 
 template <typename src_t, typename dst_t>