install/lvm2: add the dm-vdo module intruduced in Linux 6.9

Now that the Virtual Data Optimizer (VDO) kernel module dm-vdo has been upstreamed, include it in the initramfs so that it could by with LVM (see the lvmvdo(7) man page).

Reminder: all kernel modules used by LVM must be included since pvscan will not retry activating devices it could not activate in early userspace.

See also:

• https://git.kernel.org/torvalds/c/61387b8dcf1dc0f30cf690956a48768a3fce1810
• https://docs.kernel.org/admin-guide/device-mapper/vdo.html