uboot: (firmwareOdroidC2/C4) don't invoke patch tool, use patches = [] instead

https://github.com/NixOS/nixpkgs/blob/master/pkgs/stdenv/generic/setup.sh#L948
this can do it nicely.

Signed-off-by: Anton Arapov <anton@deadbeef.mx>

nixos/modules/virtualisation/azure-agent-entropy.patch

@@ -0,0 +1,17 @@
+--- a/waagent	2016-03-12 09:58:15.728088851 +0200
++++ a/waagent	2016-03-12 09:58:43.572680025 +0200
+@@ -6173,10 +6173,10 @@
+             Log("MAC  address: " + ":".join(["%02X" % Ord(a) for a in mac]))
+         
+         # Consume Entropy in ACPI table provided by Hyper-V
+-        try:
+-            SetFileContents("/dev/random", GetFileContents("/sys/firmware/acpi/tables/OEM0"))
+-        except:
+-            pass
++        #try:
++        #    SetFileContents("/dev/random", GetFileContents("/sys/firmware/acpi/tables/OEM0"))
++        #except:
++        #    pass
+ 
+         Log("Probing for Azure environment.")
+         self.Endpoint = self.DoDhcpWork()