lc15bts-mgr.cfg: Set default vswr to a value inside valid range
lc15bts-mgr.cfg: Set default vswr to a value inside valid range

Valid range is currently set to 1000-200000.

Change-Id: Ibf60ab290acf0423c7617591a86403d63266e5d3

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