xtensa: typedef enums when defining them
    
    I think this is the more typical way to do this.  Its also slightly shorter and
    less repeditive.
    
    gas/ChangeLog:
    
    2016-06-01  Trevor Saunders  <tbsaunde+binutils@tbsaunde.org>
    
    	* config/xtensa-relax.h: Move typedefs of enums to the enums
    	definition.