bitbake: hob/bitbake: save the description of a custom image

When an new image is saved, the dialog for this action has
a field for the description. Changed how an image is saved, by
appending the DESCRIPTION variable at the end of the .bb file.

[YOCTO #4193]
(Bitbake rev: 5629007f2b984005e3a8ac5d9b71422cbc2f1409)

Signed-off-by: Cristiana Voicu <cristiana.voicu@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/lib/bb/command.py

@@ -215,8 +215,9 @@ class CommandsSync:
         base_image = params[1]
         package_queue = params[2]
         timestamp = params[3]
+        description = params[4]
         return command.cooker.generateNewImage(image, base_image,
-                                 package_queue, timestamp)
+                        package_queue, timestamp, description)
 
     def ensureDir(self, command, params):
         directory = params[0]