ospf6d: turn some info->debug

ospf6d: turn some info->debug

The log is being spammed every spf interval:

Feb 27 16:19:34  ospf6d[462371]: SPF processing: # Areas: 1, SPF runtime: 0 sec 2043 usec, Reason: R+, R-, N+
Feb 27 16:20:59  ospf6d[462371]: SPF: Scheduled in 0 msec
Feb 27 16:20:59  ospf6d[462371]: SPF processing: # Areas: 1, SPF runtime: 0 sec 2284 usec, Reason: R+, R-
Feb 27 16:21:01  ospf6d[462371]: SPF: Scheduled in 0 msec
Feb 27 16:21:01  ospf6d[462371]: SPF processing: # Areas: 1, SPF runtime: 0 sec 2153 usec, Reason: R+, R-, N-

There is no reason to do this

Signed-off-by: Donald Sharp <sharpd@nvidia.com>