[DNM] west.yml: update Zephyr to kv2019i branch ff788b5

Use following Zephyr branch:

ff788b5064fa xtensa: amend exception error print with core number
36d26db583b4 xtensa: Log double exception [TEST]
0e34dcb626c6 [PATCH] L1 exit wait for interrupts completion
2dce2c3fb3f0 arch: xtensa: add isync to interrupt vector
b7078286d26d Bluetooth: audio: test: add test for long write

Signed-off-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>

west.yml

@@ -11,6 +11,8 @@ manifest:
       url-base: https://github.com/thesofproject
     - name: zephyrproject
       url-base: https://github.com/zephyrproject-rtos
+    - name: zephyrprojectkv2019i
+      url-base: https://github.com/kv2019i
 
   # When upgrading projects here please run git log --oneline in the
   # project and if not too long then include the output in your commit
@@ -43,8 +45,8 @@ manifest:
 
     - name: zephyr
       repo-path: zephyr
-      revision: 6a0b1da158a4f8bc5f2ca5058637dce26a38660e
-      remote: zephyrproject
+      revision: ff788b5064fac7fff03899aaf0f7fe233cf8f57a
+      remote: zephyrprojectkv2019i
 
       # Import some projects listed in zephyr/west.yml@revision
       #