uipc_socket: handle socket buffer locks in sopeeloff

PR: 278171
Reviewed by: markj
Fixes: a4fc41423f7d ("sockets: enable protocol specific socket buffers")
Differential Revision: https://reviews.freebsd.org/D44640

(cherry picked from commit 681711b77cde2cf3d64dc1e4951ec8287bc4f3e8)