west.yml: Remove redundant "self" key

This "self" key is optional and because we are using the repository
name, we don't need to specify it.

Signed-off-by: Yasushi SHOJI <[email protected]>

Author: yashi

west.yml

@@ -10,6 +10,3 @@ manifest:
         name-allowlist:
           - cmsis
 
-
-  self:
-    path: libcsp-zephyr