Set working directory in systemd service file

By default systemd will execute service with root directory
(or home directory for user instance) which might result in
attempts to create files in unexpected place. Let's set it
to 'osmocom' subdir of state directory
(/var/lib for system instance) instead.

Related: OS#4821
Change-Id: I041bb9e0b4250826d2d15d0ea2cdb93d7a0cd04b

contrib/systemd/osmo-trx-ipc.service

@@ -4,6 +4,8 @@ Description=Osmocom SDR BTS L1 Transceiver (IPC Backend)
 [Service]
 Type=simple
 Restart=always
+StateDirectory=osmocom
+WorkingDirectory=%S/osmocom
 ExecStart=/usr/bin/osmo-trx-ipc -C /etc/osmocom/osmo-trx-ipc.cfg
 RestartSec=2
 

contrib/systemd/osmo-trx-lms.service

@@ -4,6 +4,8 @@ Description=Osmocom SDR BTS L1 Transceiver (LimeSuite backend)
 [Service]
 Type=simple
 Restart=always
+StateDirectory=osmocom
+WorkingDirectory=%S/osmocom
 ExecStart=/usr/bin/osmo-trx-lms -C /etc/osmocom/osmo-trx-lms.cfg
 RestartSec=2
 

contrib/systemd/osmo-trx-uhd.service

@@ -4,6 +4,8 @@ Description=Osmocom SDR BTS L1 Transceiver (UHD Backend)
 [Service]
 Type=simple
 Restart=always
+StateDirectory=osmocom
+WorkingDirectory=%S/osmocom
 ExecStart=/usr/bin/osmo-trx-uhd -C /etc/osmocom/osmo-trx-uhd.cfg
 RestartSec=2
 

contrib/systemd/osmo-trx-usrp1.service

@@ -4,6 +4,8 @@ Description=Osmocom SDR BTS L1 Transceiver (libusrp backend)
 [Service]
 Type=simple
 Restart=always
+StateDirectory=osmocom
+WorkingDirectory=%S/osmocom
 ExecStart=/usr/bin/osmo-trx-usrp1 -C /etc/osmocom/osmo-trx-usrp1.cfg
 RestartSec=2