Update MCUboot version to v1.9.0

Signed-off-by: Sherry Zhang <sherry.zhang2@arm.com>
Change-Id: I0c1797984ba8aeb721cf715bdfc8ade59927a3a6
diff --git a/tf-m-cppcheck.yaml b/tf-m-cppcheck.yaml
index d04ecaa..bab5a4c 100644
--- a/tf-m-cppcheck.yaml
+++ b/tf-m-cppcheck.yaml
@@ -60,7 +60,7 @@
           default: 'https://git.trustedfirmware.org/mirror/mbed-tls.git'
       - string:
           name: 'MCUBOOT_REFSPEC'
-          default: 'v1.8.0'
+          default: 'v1.9.0'
           description: |
             Specify which MCUboot version to use
             refs/heads/master    : Pick up latest master