openhd-git: fix missing submodules

openhd-git/.SRCINFO

@@ -1,7 +1,7 @@
 pkgbase = openhd-git
 	pkgdesc = Open-source digital FPV system
-	pkgver = 2.6.0.r1.gd19b2c9
-	pkgrel = 1
+	pkgver = 2.6.0.r9.g6360d3f
+	pkgrel = 2
 	url = https://openhdfpv.org
 	arch = any
 	license = GPL3

openhd-git/PKGBUILD

@@ -2,8 +2,8 @@
 
 pkgname=openhd-git
 _reponame=OpenHD
-pkgver=2.6.0.r1.gd19b2c9
-pkgrel=1
+pkgver=2.6.0.r9.g6360d3f
+pkgrel=2
 pkgdesc='Open-source digital FPV system'
 arch=(any)
 url='https://openhdfpv.org'
@@ -24,6 +24,11 @@ pkgver() {
 	git describe --long --tags --abbrev=7 | sed 's/^v//;s/\([^-]*-g\)/r\1/;s/-/./g'
 }
 
+prepare() {
+	cd "$_reponame"
+	git submodule update --init --recursive
+}
+
 build() {
 	cmake -B build -S "$_reponame/OpenHD" -DCMAKE_INSTALL_PREFIX=/usr -Wno-dev
 	cmake --build build