aports/fp6-device-tweaks: stop the modem-gnss 30 s restart loop

pmOS's modem-gnss.service runs two qmicli calls, and the second --
--loc-set-nmea-types=all -- can never succeed on this modem: the LOC
engine answers QMI error 94 'NotSupported' to both get and set. That is
a permanent capability gap, not the boot race Restart=on-failure exists
for, so the unit failed and restarted every 30 s for the whole uptime
(restart counter 25 after 13 minutes; 165 over one evening). Its
StartLimit does not stop it either: 10 restarts at RestartSec=30 span
~303 s, just past StartLimitInterval=300.

Ship a drop-in that tolerates that one command's failure. The boot-race
retry stays armed -- a LOC service that is genuinely not up still fails
the first ExecStart. Nothing is lost: ModemManager issues its own
set-NMEA-types and takes the same 94 regardless, and location comes from
the Position Report path our modemmanager patches add.

Byte-identical to the drop-in verified on the dev phone (sha256
b0b5f71b0f25c3c5a8fc9e926f187412a6711da95f773234065f37ddcc1d3c6d):
across a reboot the unit runs once, Result=success, 0 restarts.

Assisted-by: Claude:claude-opus-5

aports/device/fp6-device-tweaks/modem-gnss-nmea-optional.conf

@@ -0,0 +1,14 @@
+# FP6 (milos): the modem LOC engine does not implement NMEA-type configuration
+# at all -- both --loc-get-nmea-types and --loc-set-nmea-types return
+# QMI protocol error (94) NotSupported. That is a permanent engine capability,
+# not a boot race, so the unit's Restart=on-failure retried it every 30 s
+# forever (StartLimitBurst=10/StartLimitInterval=300 never trips: 10 restarts
+# at RestartSec=30 span ~303 s > 300 s). NMEA sentences are delivered by the
+# engine regardless -- on-device fixes carry RMC.
+#
+# Tolerate the failure of that one command; a genuinely-not-up LOC service
+# still fails the first ExecStart and keeps the intended boot-race retry.
+[Service]
+ExecStart=
+ExecStart=qmicli -d qrtr://0 --loc-set-engine-lock=mt
+ExecStart=-qmicli -d qrtr://0 --loc-set-nmea-types=all