osmocom-bb for ms-trx side trxcon integration

Change-Id: I784a3d66b68f6458056d92db2ec596755b704e61
diff --git a/.gitmodules b/.gitmodules
new file mode 100644
index 0000000..bc94e80
--- /dev/null
+++ b/.gitmodules
@@ -0,0 +1,4 @@
+[submodule "osmocom-bb"]
+	path = osmocom-bb
+	url = https://gitea.osmocom.org/phone-side/osmocom-bb.git
+	branch = a4aac5c3554559c2c994609f90b92a9daf6e8a89