oc2g: Cleanup of get_hwversion_desc
oc2g: Cleanup of get_hwversion_desc

Remove unused variables, wrong return type values, etc.

Change-Id: I5565b904c72a9ac1775818416f05c64722d366b2

osmocom/osmo-bts,osmocom/osmo-bts,osmocom/osmo-bts