selftests: net: lib: fix shift count out of range

selftests: net: lib: fix shift count out of range

I got the following warning when writing other tests:

  + handle_test_result_pass 'bond 802.3ad' '(lacp_active off)'
  + local 'test_name=bond 802.3ad'
  + shift
  + local 'opt_str=(lacp_active off)'
  + shift
  + log_test_result 'bond 802.3ad' '(lacp_active off)' ' OK '
  + local 'test_name=bond 802.3ad'
  + shift
  + local 'opt_str=(lacp_active off)'
  + shift
  + local 'result= OK '
  + shift
  + local retmsg=
  + shift
  /net/tools/testing/selftests/net/forwarding/../lib.sh: line 315: shift: shift count out of range

This happens because an extra shift is executed even after all arguments
have been consumed. Remove the last shift in log_test_result() to avoid
this warning.

Fixes: a923af1ceee7 ("selftests: forwarding: Convert log_test() to recognize RET values")
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Link: https://patch.msgid.link/20250709091244.88395-1-liuhangbin@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>