Update gvc submodule to the latest commit from master

This avoids unnecessary calls to match_card_port_with_existing_device()
when connecting to a bluetooth device from the shell's top panel.

https://bugzilla.gnome.org/show_bug.cgi?id=752675

diff --git a/src/gvc b/src/gvc
index e14dbe8aa6dfaeea4a9f3405cf2f3e238e88623b..fac3a900e5de2c60d667c54f2727e806d29cff4b 160000 (submodule)
--- a/src/gvc
+++ b/src/gvc
@@ -1 +1 @@
-Subproject commit e14dbe8aa6dfaeea4a9f3405cf2f3e238e88623b
+Subproject commit fac3a900e5de2c60d667c54f2727e806d29cff4b