In r340042 an attempt to quiet coverity warning cid 1305412 was overdone.
nopt is the only allocated space,
xopt and cp are aliases into that allocated space.
Remove the 2 unneeded free's

Reported by: Patrick Mooney (@pmooney_pfmooney.com)
Reviewed by: jhb (maintainer), Patrick Mooney (joyent/illumos)
Approved by: bde (mentor)
CID: 1305412
MFC after: 3 days
MFC with: 340042
Differential Revision: https://reviews.freebsd.org/D19200