Add QemuMacDrivers as submodule

The QemuMacDrivers project provides virtualisation drivers for PPC MacOS
guests.

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
diff --git a/.gitmodules b/.gitmodules
index ca323b4..5b0c212 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -34,3 +34,6 @@
 [submodule "roms/skiboot"]
 	path = roms/skiboot
 	url = git://git.qemu.org/skiboot.git
+[submodule "roms/QemuMacDrivers"]
+	path = roms/QemuMacDrivers
+	url = git://git.qemu.org/QemuMacDrivers.git