ospf6d: Type-7 LSA originated with wrong sequence number

ospf6d: Type-7 LSA originated with wrong sequence number

RCA: When Type-7 LSA is updated, the LSDB is searched, if the
LSA is present in the LSDB then the LSA is updated with next
sequence number and if not then it is originated with the
INITIAL sequence number.
Here while originating Type-7 LSA Process Level LSDB is searched
for instead of area level LSDB.

Fix: Search in the area level LSDB and not in the process level.

Fixes #9099

Signed-off-by: Mobashshera Rasool <mrasool@vmware.com>