Correct the name of the structure used for TCP socket options.

The structure was renamed while refactoring Netflix's KTLS changes for
upstreaming, but the original name remained in tcp.4 and was
subsequently copied to ktls.4.

PR:		254141
Reported by:	asomers
MFC after:	3 days

share/man/man4/ktls.4

@@ -31,7 +31,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd February 8, 2021
+.Dd March 8, 2021
 .Dt KTLS 4
 .Os
 .Sh NAME
@@ -54,7 +54,7 @@ and
 .Dv TCP_RXTLS_ENABLE
 socket options.
 Both socket options accept a
-.Vt struct tls_so_enable
+.Vt struct tls_enable
 structure as their argument.
 The members of this structure describe the cipher suite used for the
 TLS session and provide the session keys used for the respective
@@ -166,7 +166,7 @@ will fail with one of the following errors:
 .It Bq Er EINVAL
 The version fields in a TLS record's header did not match the version required
 by the
-.Vt struct tls_so_enable
+.Vt struct tls_enable
 structure used to enable in-kernel TLS.
 .It Bq Er EMSGSIZE
 A TLS record's length was either too small or too large.