linux-purism-librem5: upgrade to 6.0.0

• the config diff is just rebasing

• drops the ship mode patch I wrote, since it is no longer required after a pending update to the device-purism-librem5 package...

• drops the dogwood voltage patch, apparently no longer necessary, see: https://source.puri.sm/Librem5/linux/-/issues/442#note_214984

• drops the usdhc bus patch see: https://source.puri.sm/Librem5/linux/-/issues/442#note_215026