[PATCH net] l2tp: ppp: use max L2TP header size for PPP channel hdrlen

Spam detection software, running on the system "ciao.gmane.io",
has identified this incoming email as possible spam.  The original
message has been attached to this so you can view it or label
similar future email.  If you have any questions, see
@@CONTACT_ADDRESS@@ for details.

Content preview:  chan.hdrlen is read once at channel registration by ppp_register_net_channel(),
   and used to set the PPP net device's hard_header_len. It was set to PPPOL2TP_L2TP_HDR_SIZE_NOSEQ
   (6), which is 4 bytes t [...] 

Content analysis details:   (5.0 points, 5.0 required)

 pts rule name              description
---- ---------------------- --------------------------------------------------
 3.4 FSL_HELO_FAKE          No description available.
 0.0 DKIM_ADSP_CUSTOM_MED   No valid author signature, adsp_override is
                             CUSTOM_MED
 1.0 FORGED_GMAIL_RCVD      'From' gmail.com does not match 'Received'
                            headers
 0.0 FREEMAIL_FROM          Sender email is commonly abused enduser mail
                            provider (dqfext[at]gmail.com)
 0.2 HEADER_FROM_DIFFERENT_DOMAINS From and EnvelopeFrom 2nd level
                            mail domains are different
 0.1 DKIM_SIGNED            Message has a DKIM or DK signature, not necessarily
                            valid
 1.3 RCVD_IN_RP_RNBL        RBL: Relay in RNBL,
                            https://senderscore.org/blacklistlookup/
                           [172.232.135.74 listed in bl.score.senderscore.com]
 0.0 T_DKIM_INVALID         DKIM-Signature header exists but is not valid
-1.0 MAILING_LIST_MULTI     Multiple indicators imply a widely-seen list
                            manager
 0.0 FREEMAIL_FORGED_FROMDOMAIN 2nd level domains in From and
                            EnvelopeFrom freemail headers are
                            different