Remove network specific default and max log level setting
and start to use the zephyr logging values for those.
Remove LOG_MODULE_REGISTER() from net_core.h and place the
calls into .c files. This is done in order to avoid weird
compiler errors in some cases and to make the code look similar
as other subsystems.
Fixes#11343Fixes#11659
Signed-off-by: Jukka Rissanen <jukka.rissanen@linux.intel.com>