fix branches of qtpim and qtsystems

these repos were definitely _not_ branched for 5.7.

Change-Id: Ib31d4e07f2651cfba0a7d31a9db1f1a812061313
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>
Reviewed-by: Liang Qi <liang.qi@qt.io>

.gitmodules

@@ -110,7 +110,7 @@
 	recommends = qtdeclarative
 	path = qtsystems
 	url = ../qtsystems.git
-	branch = 5.7
+	branch = dev
 	status = ignore
 [submodule "qtfeedback"]
 	depends = qtdeclarative
@@ -129,7 +129,7 @@
 	depends = qtdeclarative
 	path = qtpim
 	url = ../qtpim.git
-	branch = 5.7
+	branch = dev
 	status = ignore
 [submodule "qtconnectivity"]
 	depends = qtbase