west.yml: update Zephyr for IPC rework [DNM]

DO NOT MERGE! DO NOT MERGE!

Update Zephyr for IPC rework.

Signed-off-by: Daniel Leung <daniel.leung@intel.com>

Author: dcpleung

west.yml

@@ -43,7 +43,7 @@ manifest:
 
     - name: zephyr
       repo-path: zephyr
-      revision: 9075d5335596080291ebcc448819fed2110dcb9a
+      revision: pull/91606/head
       remote: zephyrproject
 
       # Import some projects listed in zephyr/west.yml@revision