celp_math: Replace duplicate ff_dot_productf() by ff_scalarproduct_c()

libavcodec/celp_math.c

@@ -86,14 +86,3 @@ int ff_log2(uint32_t value)
 
     return (power_int << 15) + value;
 }
-
-float ff_dot_productf(const float* a, const float* b, int length)
-{
-    float sum = 0;
-    int i;
-
-    for(i=0; i<length; i++)
-        sum += a[i] * b[i];
-
-    return sum;
-}