Cleanup: remove hard coded file format check in IMB_ispic_type

This is already being checked in the 'is_a' callback.

source/blender/imbuf/intern/util.c

@@ -152,11 +152,6 @@ int IMB_ispic_type(const char *name)
 
   close(fp);
 
-  /* XXX move this exception */
-  if ((BIG_LONG(((int *)buf)[0]) & 0xfffffff0) == 0xffd8ffe0) {
-    return IMB_FTYPE_JPG;
-  }
-
   for (type = IMB_FILE_TYPES; type < IMB_FILE_TYPES_LAST; type++) {
     if (type->is_a) {
       if (type->is_a(buf)) {