hdlc_ppp: fix potential null pointer in ppp_cp_event logging

drivers/net/wan/hdlc_ppp.c: In function ‘ppp_cp_event’:
drivers/net/wan/hdlc_ppp.c:353:17: warning: ‘%s’ directive argument is null [-Wformat-overflow=]
  353 |                 netdev_info(dev, "%s down\n", proto_name(pid));
      |                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/net/wan/hdlc_ppp.c:342:17: warning: ‘%s’ directive argument is null [-Wformat-overflow=]
  342 |                 netdev_info(dev, "%s up\n", proto_name(pid));
      |                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Update proto_name() to return "LCP" by default instead of NULL.
This change silences the compiler without changing existing behavior
and removes the need for the local 'pname' variable in ppp_cp_event.

Suggested-by: Krzysztof Hałasa <khalasa@piap.pl>
Signed-off-by: Kriish Sharma <kriish.sharma2006@gmail.com>
Acked-by: Krzysztof Hałasa <khalasa@piap.pl>
Link: https://patch.msgid.link/20251013014319.1608706-1-kriish.sharma2006@gmail.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

1 file changed