Arm32: leave more .bfloat16 processing to common code

With x86 support having been implemented by extending atof-ieee.c, avoid
unnecessary code duplication in md_atof(). This will then also allow to
take advantage of adjustments made there without needing to mirror them
here.

gas/config/tc-arm.c

@@ -1247,55 +1247,12 @@ md_atof (int type, char * litP, int * sizeP)
     {
     case 'H':
     case 'h':
+    /* bfloat16, despite not being part of the IEEE specification, can also
+       be handled by atof_ieee().  */
+    case 'b':
       prec = 1;
       break;
 
-    /* If this is a bfloat16, then parse it slightly differently, as it
-       does not follow the IEEE specification for floating point numbers
-       exactly.  */
-    case 'b':
-      {
-	FLONUM_TYPE generic_float;
-
-	t = atof_ieee_detail (input_line_pointer, 1, 8, words, &generic_float);
-
-	if (t)
-	  input_line_pointer = t;
-	else
-	  return _("invalid floating point number");
-
-	switch (generic_float.sign)
-	  {
-	  /* Is +Inf.  */
-	  case 'P':
-	    words[0] = 0x7f80;
-	    break;
-
-	  /* Is -Inf.  */
-	  case 'N':
-	    words[0] = 0xff80;
-	    break;
-
-	  /* Is NaN.  */
-	  /* bfloat16 has two types of NaN - quiet and signalling.
-	     Quiet NaN has bit[6] == 1 && faction != 0, whereas
-	     signalling NaN's have bit[0] == 0 && fraction != 0.
-	     Chosen this specific encoding as it is the same form
-	     as used by other IEEE 754 encodings in GAS.  */
-	  case 0:
-	    words[0] = 0x7fff;
-	    break;
-
-	  default:
-	    break;
-	  }
-
-	*sizeP = 2;
-
-	md_number_to_chars (litP, (valueT) words[0], sizeof (LITTLENUM_TYPE));
-
-	return NULL;
-      }
     case 'f':
     case 'F':
     case 's':