MAINTAINERS: Add myself as VKMS Maintainer

I've been actively working on VKMS to provide new features and
participated in reviews and testing. To help Maìra with her work, add
myself as co-maintainer of VKMS.

Signed-off-by: Louis Chauvet <louis.chauvet@bootlin.com>
Acked-by: Maíra Canal <mcanal@igalia.com>
Signed-off-by: Maíra Canal <mcanal@igalia.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240910-vkms-maintainer-v1-1-e7a6c7a4ae71@bootlin.com