MAINTAINERS: Hand over phy-zynqmp to Tomi Valkeinen

I volunteered to maintain the phy-zynqmp driver as part of my work on
the ZynqMP DPSUB driver. Now that Tomi has taken over the DPSUB, it
makes sense for him to handle the phy-zynqmp driver as well.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Acked-by: Radhey Shyam Pandey <radhey.shyam.pandey@amd.com>
Link: https://patch.msgid.link/20260519082253.40142-1-laurent.pinchart@ideasonboard.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>