g723.1: simplify normalize_bits()

This function is always called with a non-negative argument, so
those special cases are not needed.  In the places the argument
might be zero, the return value for a zero argument does not matter
since it would then be used to scale an array full of zeros.
Signed-off-by: Mans Rullgard <mans@mansr.com>

libavcodec/g723_1.c

@@ -265,13 +265,6 @@ static int16_t square_root(int val)
  */
 static int normalize_bits(int num, int width)
 {
-    if (!num)
-        return 0;
-    if (num == -1)
-        return width;
-    if (num < 0)
-        num = ~num;
-
     return width - av_log2(num) - 1;
 }