Remove xtr id mappings on mapping overwrite

Remove xtr id mappings on mapping overwrite

If there are 2 xtrs with different merge mapping configuration
registers same eid, we may or may not have merged mapping for
the eid in Map Cache but we will have xtr id specific mapping
in XTRID_RECORDS all the time. When we have xtr id specific
mapping from the xtr with merge configuration, but overwritten
mapping record in RECORD, then the xtr id specific mappings
may become untracked and hence not removed ever.

This patch removes previous xtrid specific mappings too when
mapping records are being overwritten.

Change-Id: Iaf8686367fb881b5794a3bf232e6c2e12d5ec6f8
Signed-off-by: Shakib Ahmed <sheikahm@cisco.com>