Enable cppcoreguidelines-init-variables

We try to enforce this rule, but clearly the robot can do a better job.
Enable the rule, and for init of all variables that clang-tidy finds in
error.

Signed-off-by: Ed Tanous <edtanous@google.com>
Change-Id: Icf64bc51b3180de29f7e92fa5c5f636e6b1462a6
diff --git a/src/IpmbSensor.cpp b/src/IpmbSensor.cpp
index b2c9dd2..7c76d3b 100644
--- a/src/IpmbSensor.cpp
+++ b/src/IpmbSensor.cpp
@@ -188,11 +188,11 @@
     else if (type == IpmbType::ADM1278HSC)
     {
         commandAddress = meAddress;
+        uint8_t snsNum = 0;
         switch (subType)
         {
             case IpmbSubType::temp:
             case IpmbSubType::curr:
-                uint8_t snsNum;
                 if (subType == IpmbSubType::temp)
                 {
                     snsNum = 0x8d;