[CPS] update .gitreview for london

- update .gitreview for dmi-plugin to change defaultbranch from master
  to london
- Step 13 of the release process

Issue-ID: CPS-1611
Change-Id: I783b3b273caeb50ad1bd4b95b3e451bfb404d86f
Signed-off-by: mpriyank <priyank.maheshwari@est.tech>
1 file changed