manifest: sof: update to commit e7cb489d4

This updates SOF modules to commit
e7cb489d430dc2181e4a5f7f953ed1eaeec6668d. This includes
a change where rimage is pulled into the tree and is no
longer a submodule. So update the rimage config path so
signing still works.

Signed-off-by: Daniel Leung <daniel.leung@intel.com>
diff --git a/scripts/west_commands/sign.py b/scripts/west_commands/sign.py
index 87b8346..bdf9d35 100644
--- a/scripts/west_commands/sign.py
+++ b/scripts/west_commands/sign.py
@@ -502,7 +502,7 @@
         elif cache.get('RIMAGE_CONFIG_PATH'):
             conf_dir = pathlib.Path(cache['RIMAGE_CONFIG_PATH'])
         else:
-            conf_dir = sof_src_dir / 'rimage' / 'config'
+            conf_dir = sof_src_dir / 'tools' / 'rimage' / 'config'
 
         conf_path_cmd = ['-c', str(conf_dir / cmake_toml)] if conf_dir else []