manifest: update mcuboot reference

This is needed to include changes from
mcu-tools/mcuboot#2222

Signed-off-by: Valerio Setti <[email protected]>

Author: valeriosetti

Diff for: west.yml

@@ -23,6 +23,8 @@ manifest:
       url-base: https://github.com/zephyrproject-rtos
     - name: babblesim
       url-base: https://github.com/BabbleSim
+    - name: mcuboot_upstream
+      url-base: https://github.com/mcu-tools
 
   group-filter: [-babblesim, -optional]
 
@@ -303,7 +305,8 @@ manifest:
       groups:
         - crypto
     - name: mcuboot
-      revision: 346f7374ff4467e40b5594658f8ac67a5e9813c9
+      remote: mcuboot_upstream
+      revision: pull/2222/head
       path: bootloader/mcuboot
       groups:
         - bootloader