misc: Updated MAINTAINERS.yaml

misc: Updated MAINTAINERS.yaml

Change-Id: Ibda441858a22c9e8bb22e132c165e7724aaf7539
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/37356
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br>
Reviewed-by: Matt Sinclair <mattdsinclair@gmail.com>
Reviewed-by: Matthew Poremba <matthew.poremba@amd.com>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Maintainer: Matt Sinclair <mattdsinclair@gmail.com>
Maintainer: Bobby R. Bruce <bbruce@ucdavis.edu>
Tested-by: kokoro <noreply+kokoro@google.com>