ping: tests: Cleanup IPOption()s
Scapy now only accepts known options with IPOption(), so our unknown
option must be passed raw.
While here, prefer the named options for EOL and NOP.
Reviewed by: emaste, kp
Approved by: emaste (mentor)
Differential Revision: https://reviews.freebsd.org/D47160
(cherry picked from commit 2e29bf7a2ae66acb6e65ffc1c923cfb373af67bd)