remove vpalatin from OWNERS

An update on the OWNERS file:
remove vpalatin from the owners of modemmanager related projects.

BUG=None
TEST=None

Change-Id: Ie76cbc16fb19fdb7e0f2ab6020eb5d46d4bec483
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/modemmanager-next/+/3047991
Tested-by: Vincent Palatin <vpalatin@chromium.org>
Auto-Submit: Vincent Palatin <vpalatin@chromium.org>
Reviewed-by: Eric Caruso <ejcaruso@chromium.org>
Commit-Queue: Eric Caruso <ejcaruso@chromium.org>