The technical specification TS 36.414 section 5.4 Diffserv code point marking says:
“IP Differentiated Services code point marking shall be supported. The mapping between traffic categories and Diffserv code points shall be configurable by O&M based on QoS Class Identifier (QCI) Characteristics and others E-UTRAN traffic parameters. Traffic categories are implementation-specific and may be determined from the application parameters”
which means, that there is DSCP marking for Outer IP Header (above GTP) let us know if you have any doubt further?