ospfd: do not complain if same area is reconfigured

ospfd: do not complain if same area is reconfigured

Signed-off-by: Daniel Walton <dwalton@cumulusnetworks.com>
Before
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cel-redxp-10(config)# router ospf vrf RED
cel-redxp-10(config-router)# network 1.1.1.1/32 area 0.0.0.0
cel-redxp-10(config-router)# network 1.1.1.1/32 area 0.0.0.0
There is already same network statement.
cel-redxp-10(config-router)#

When we see the "There is already same network statement." message
vtysh exits non-zero.  This scenario breaks frr-reload because
the command took and it in the config, it should exit zero here.

After
-----
cel-redxp-10(config)# router ospf vrf RED
cel-redxp-10(config-router)# network 1.1.1.1/32 area 0.0.0.0
cel-redxp-10(config-router)# network 1.1.1.1/32 area 0.0.0.0
cel-redxp-10(config-router)# network 1.1.1.1/32 area 0.0.0.0
cel-redxp-10(config-router)# network 1.1.1.1/32 area 0
cel-redxp-10(config-router)#
cel-redxp-10(config-router)# network 1.1.1.1/32 area 0.0.0.1
There is already same network statement.
cel-redxp-10(config-router)#