samples: mpu_test: verify sample using shell harness

Verify sample using shell harness instead of just building the sample.

Signed-off-by: Anas Nashif <anas.nashif@intel.com>

samples/arch/mpu/mpu_test/sample.yaml

diff --git a/samples/arch/mpu/mpu_test/sample.yaml b/samples/arch/mpu/mpu_test/sample.yaml
index ca604ed..49f97f3 100644
--- a/samples/arch/mpu/mpu_test/sample.yaml
+++ b/samples/arch/mpu/mpu_test/sample.yaml
@@ -4,5 +4,6 @@
   sample.mpu.mpu_test:
     arch_allow: arm
     filter: CONFIG_CPU_HAS_MPU and not CONFIG_ARM64
-    tags: mpu
-    harness: keyboard
+    tags:
+      - mpu
+    harness: shell

samples/arch/mpu/mpu_test/test_shell.yml

diff --git a/samples/arch/mpu/mpu_test/test_shell.yml b/samples/arch/mpu/mpu_test/test_shell.yml
new file mode 100644
index 0000000..36815e9
--- /dev/null
+++ b/samples/arch/mpu/mpu_test/test_shell.yml
@@ -0,0 +1,5 @@
+test_shell_harness:
+- command: "mpu mtest 1"
+  expected: "The value is: 0x.*"
+- command: "mpu mtest 2"
+  expected: "The value is: 0x.*"