Fix (-W)documentation error found by Clang

Fix (-W)documentation error found by Clang

../../epan/range.h:87:11: error: empty paragraph passed to '@return' command [-Werror,-Wdocumentation]
 * @return
   ~~~~~~~^
../../epan/range.h:86:11: error: parameter 'max_value'' not found in the function declaration [-Werror,-Wdocumentation]
 * @param max_value' specifies the maximum value in a range.
          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../../epan/range.h:86:11: note: did you mean 'max_value'?
 * @param max_value' specifies the maximum value in a range.
          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
          max_value

svn path=/trunk/; revision=51256