Since August 2022, users of very old Turris Omnias have been
encouraged to update U-Boot before OpenWrt installation [1].
The omnia-medkit (only useful for installation with
U-Boot 2015.10-rc2) is not needed anymore.
[1] https://openwrt.org/toh/turris/turris_omnia#installation
Signed-off-by: Klaus Kudielka <klaus.kudielka@gmail.com>