wic: isoimage: do not remove temp directory

Removed isodir subrdirectory instead of removing temporary
working directory as working directory can contain copy of
rootfs partition and shouldn't be removed by any plugin.

(From OE-Core rev: fc12ce9d1b92cc0104cf456af1e3d5f146b9219d)

Signed-off-by: Ed Bartosh <ed.bartosh@linux.intel.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

scripts/lib/wic/plugins/source/isoimage-isohybrid.py

@@ -204,8 +204,8 @@ class IsoImagePlugin(SourcePlugin):
         """
         isodir = "%s/ISO/" % cr_workdir
 
-        if os.path.exists(cr_workdir):
-            shutil.rmtree(cr_workdir)
+        if os.path.exists(isodir):
+            shutil.rmtree(isodir)
 
         install_cmd = "install -d %s " % isodir
         exec_cmd(install_cmd)