Changes

osmo-trx-uhd: Make sure HOME environment variable is set

It turns out that uhd versions >= 4.0.0.0 *require* that either the
HOME or the XDG_CONFIG_HOME variables are set, and otherwise will
terminate the program.

Change-Id: I1816013c507da28719590f063da0a397da656a10
Closes: OS#6269
(cherry picked from commit 6ee9dccddb916e44b6bb3e2c967d8a37078206b4)