octphy VTY: fix vty write output for octphy's phy section
octphy VTY: fix vty write output for octphy's phy section

Fix invalid configuration generated by VTY 'write' command for the 'phy'
section of osmo-bts-octphy.

The problem was introduced during refactoring
commit d784e50747b8cf0ce505489e1451f75be5ccbd4b (Sat Jan 9 13:13:37
2016 +0100, "Introduce new phy_link and phy_instance abstraction")

Change-Id: Ib018e07e332aa8a6144fb2d87889032bd5fc2533

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