graphics: update owners

With olv@ no longer on the graphics team we need to update the
owners file to remove him and add new owners.

For composer the new owners are: lpy@ and vhau@
For allocator/mapper the new owner is: marissaw@

Test: N/A
Change-Id: Ied297e9446d480629155e1d9a96575ee518c2135
diff --git a/graphics/composer/2.1/utils/OWNERS b/graphics/composer/2.1/utils/OWNERS
index d515a23..5acc631 100644
--- a/graphics/composer/2.1/utils/OWNERS
+++ b/graphics/composer/2.1/utils/OWNERS
@@ -1,4 +1,5 @@
 courtneygo@google.com
 jessehall@google.com
-olv@google.com
+lpy@google.com
 stoza@google.com
+vhau@google.com