Add phoglund as root owner.

It seems convenient since the EngProd team make repo-wide changes
every now and then.

Bug: None
Change-Id: If429fc8ed503a3c24c912ac2e8d120f93edc4823
Reviewed-on: https://webrtc-review.googlesource.com/77760
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Reviewed-by: Magnus Flodman <mflodman@webrtc.org>
Reviewed-by: Tommi <tommi@webrtc.org>
Reviewed-by: Henrik Andreassson <henrika@webrtc.org>
Reviewed-by: Stefan Holmer <stefan@webrtc.org>
Reviewed-by: Niklas Enbom <niklas.enbom@webrtc.org>
Commit-Queue: Niklas Enbom <niklas.enbom@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#23312}