DscpPolicy: remove bpf support for raw ip

This program was only used for tests as WiFi interfaces should always
include an ethernet header. Since the test has moved from tun to tap,
this can be deleted.
Support for using this program was already removed in a previous CL.

Test: TH
Bug: 235559605
Change-Id: I2148bce60992070790ba237176b99a40597ee751