tests: e1inp_ipa_bts_test: fix compilation warnings

  CC     e1inp_ipa_bts_test.o
e1inp_ipa_bts_test.c: In function ‘sign_link_up’:
e1inp_ipa_bts_test.c:47:8: warning: variable ‘dst’ set but not used [-Wunused-but-set-variable]
e1inp_ipa_bts_test.c: In function ‘test_bts_gsm_12_21_cb’:
e1inp_ipa_bts_test.c:211:6: warning: variable ‘ret’ set but not used [-Wunused-but-set-variable]
  CCLD   e1inp_ipa_bts_test
1 file changed