misc,base: Update the version to v21.2.1.0

Change-Id: Ic92d2c6f23b5618896fdf6e19dc1e5f0c6d14238
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/56251
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
2 files changed