n_hdlc: remove useless whitespace at line wraps

Do
  s@[ \t]\+$@@
  s@ \+\t@\t@
on the file as there are many spaces at the begininning of lines and
many spaces/tabs at EOLs. And vim screamed.

git show -w is supposed to show no difference here.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20200219084118.26491-20-jslaby@suse.cz


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>