meta-palmetto: Fix issues found by HW CI

HW CI on Palmetto trigers two issues:
1. The case to verify occ active fails because it was using the last
   character of `cpux` for occ, e.g. cpu0 -> occ0.
   Palmetto had an incorrect inventory path of `cpu`, which results in
   `occu`, and it becomes an incorrect path, and the case gets a 404
   error while trying to get the OCC active state.
2. The case to get https://$bmc/ fails, it's expecting HTTP 200 OK
   resonse, but got a 401 error. This is because webui is not built into
   Palmetto, so there is no page, and bmcweb returns 401 for such case.

Fix the above cases.

Tested: Verify the HW CI succeeds on Palmetto:

    python3 -m robot -v OPENBMC_HOST:palmetto --argumentfile \
        test_lists/HW_CI --exclude Verify_Redfish_Host_PowerOn --include \
        Verify_Redfish_Host_PowerOn_No_Check_Watts  redfish  tests

Signed-off-by: Lei YU <mine260309@gmail.com>
Change-Id: Ibf46c6d95f09638634418fda5049d8f37125d65d
diff --git a/meta-palmetto/recipes-phosphor/configuration/palmetto-yaml-config/palmetto-ipmi-sensors.yaml b/meta-palmetto/recipes-phosphor/configuration/palmetto-yaml-config/palmetto-ipmi-sensors.yaml
index 372ad2d..349b8b9 100644
--- a/meta-palmetto/recipes-phosphor/configuration/palmetto-yaml-config/palmetto-ipmi-sensors.yaml
+++ b/meta-palmetto/recipes-phosphor/configuration/palmetto-yaml-config/palmetto-ipmi-sensors.yaml
@@ -584,7 +584,7 @@
                         deassert: false
                         type: bool
     mutability: Mutability::Write|Mutability::Read
-    path: /system/chassis/motherboard/cpu
+    path: /system/chassis/motherboard/cpu0
     readingType: assertion
     sensorNamePattern: nameLeaf
     sensorReadingType: 111