google-sargo: move openrc gnss service to openrc subpackage

On a new installation, the OpenRC subpackage can be installed before the
main package. The modem-gnss service is already needed when the
subpackage is installed. Move the service file to the subpackage so new
installations don't error out.

    ( 66/750) Installing device-google-sargo-openrc (13-r0)
    device-google-sargo-openrc-13-r0.post-install: Executing script...
    device-google-sargo-openrc-13-r0.post-install:  * service hexagonrpcd-adsp-sensorspd added to runlevel sysinit
    device-google-sargo-openrc-13-r0.post-install:  * rc-update: service `modem-gnss' does not exist
    ERROR: device-google-sargo-openrc-13-r0.post-install: exited with error 1
    ...
    (199/750) Installing device-google-sargo (13-r0)
    ...
    1 error; 1335 MiB in 766 packages

Link: https://builds.sr.ht/~postmarketos/job/1542762#task-img

Part-of: https://gitlab.postmarketos.org/postmarketOS/pmaports/-/merge_requests/6866

device/community/device-google-sargo/APKBUILD

@@ -3,7 +3,7 @@
 pkgname=device-google-sargo
 pkgdesc="Google Pixel 3a"
 pkgver=13
-pkgrel=0
+pkgrel=1
 url="https://postmarketos.org"
 license="MIT"
 arch="aarch64"
@@ -60,9 +60,6 @@ package() {
 	# via non-free firmware.
 	install -Dm644 "$srcdir"/q6voiced.conf "$pkgdir"/etc/conf.d/q6voiced
 
-	install -Dm755 "$srcdir"/modem-gnss.initd \
-		"$pkgdir"/etc/init.d/modem-gnss
-
 	install -Dm755 "$srcdir"/modem-gnss.service \
 		-t "$pkgdir"/usr/lib/systemd/system
 }
@@ -77,6 +74,9 @@ openrc() {
 	# The FastRPC service is only enabled when non-free firmware is installed.
 	install -Dm755 "$srcdir"/no-hexagonrpcd-on-suspend.sh \
 		"$subpkgdir"/etc/elogind/system-sleep/no-hexagonrpcd-on-suspend.sh
+
+	install -Dm755 "$srcdir"/modem-gnss.initd \
+		"$pkgdir"/etc/init.d/modem-gnss
 }
 
 plasma_camera() {