doc: renesas: Update code owner for Renesas platforms

Add Marek Vasut as the code owner for the common code shared by
both Renesas R-Car and RZ/G2 platforms.

Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Change-Id: I3c0a402f4663ffcf4d2df408a3ccd4d1a8629b3a
diff --git a/docs/about/maintainers.rst b/docs/about/maintainers.rst
index 5ac1730..7c91e18 100644
--- a/docs/about/maintainers.rst
+++ b/docs/about/maintainers.rst
@@ -482,7 +482,9 @@
 :M: Marek Vasut <marek.vasut@gmail.com>
 :G: `marex`_
 :F: docs/plat/rcar-gen3.rst
+:F: plat/renesas/common
 :F: plat/renesas/rcar
+:F: drivers/renesas/common
 :F: drivers/renesas/rcar
 :F: tools/renesas/rcar_layout_create
 
@@ -490,6 +492,8 @@
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^
 :M: Biju Das <biju.das.jz@bp.renesas.com>
 :G: `bijucdas`_
+:M: Marek Vasut <marek.vasut@gmail.com>
+:G: `marex`_
 :F: docs/plat/rz-g2.rst
 :F: plat/renesas/common
 :F: plat/renesas/rzg