ospfd: Add ospf_lsa_new_and_data function and abstract away

ospfd: Add ospf_lsa_new_and_data function and abstract away

In all but one instance we were following this pattern
with ospf_lsa_new:

ospf_lsa_new()
ospf_lsa_data_new()

so let's create a ospf_lsa_new_and_data to abstract
this bit of fun and cleanup all the places where
it assumes these function calls can fail.

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