update kernel to 6.2.16 & ZFS to 2.1.11, drop outdated patches

update kernel to 6.2.16 & ZFS to 2.1.11, drop outdated patches

switch to our new unified ubuntu-kernels git origin, allows for
simpler update (no buildsys change required anymore)

The two patches dropped are:

- removal of xr-usb-uart, which was patched in by ubuntu (thus no
  KConfig switch, and got now removed, see:
  https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1945938
- a fix for a syntax error in Ubuntu patches, which is fixed in newer
  repo already

Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>