fw_printenv and fw_setenv not available on Ubuntu 18.04.5 LTS

Hi there

In the latest release of u-boot-tools both commands "fw_printenv" and "fw_setenv" was removed from package.

Changelog for 2020.10+dfsg-1ubuntu0~18.04.2 package contain following line:

" - Remove fw_printenv and fw_setenv and Recommend libubootenv-tool.
      (Closes: #939598)
"

Bug number 939598 is referencing to the Debian bugzilla (https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=939598)

As I can see, fw_setenv and fw_printenv was removed from Debian package due to conflict with same binaries in package libubootenv-tool. However, this package is available only in Ubuntu 20 but not in Ubuntu 18.

There is no alternative package containing this files: https://packages.ubuntu.com/search?searchon=contents&keywords=fw_setenv&mode=exactfilename&suite=bionic-updates&arch=any

More to say, "file-not-found" command is referencing to "u-boot-tools" command:

```
# apt install u-boot-tools
Reading package lists... Done
Building dependency tree
Reading state information... Done
u-boot-tools is already the newest version (2020.10+dfsg-1ubuntu0~18.04.2).
0 upgraded, 0 newly installed, 0 to remove and 55 not upgraded.

# fw_printenv

Command 'fw_printenv' not found, but can be installed with:

apt install u-boot-tools
```

Please provide alternative package for Ubuntu 18.04 (e.g libubootenv-tool) because this is breaking change