LU-7734 lnet: double free in lnet_add_net_common()

LU-7734 lnet: double free in lnet_add_net_common()

lnet_startup_lndnet() always consumes its net parameter, so we
should not free net after the function has been called. This
fixes a double free triggered by adding a network twice.

Eliminate the netl local variable.

Signed-off-by: Olaf Weber <olaf@sgi.com>
Change-Id: I1cfc3494eada4660b792f6a1ebd96b5dc80d9945
Reviewed-on: http://review.whamcloud.com/21446
Reviewed-by: Amir Shehata <amir.shehata@intel.com>
Tested-by: Amir Shehata <amir.shehata@intel.com>