vti4: removed duplicate log message.

Removed info log-message if ipip tunnel registration fails during
module-initialization: it adds nothing to the error message that is
written on all failures.

Fixes: dd9ee344 ("vti4: Fix a ipip packet processing bug in 'IPCOMP' virtual tunnel")
Signed-off-by: Jeremy Sowden <jeremy@azazel.net>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>