PRD: Fix reading of NVDIMM ES_TEMP value

Change-Id: I6734afee576b4f46c569d26ecf96fe287a85cf80
CQ: SW475263
Reviewed-on: http://rchgit01.rchland.ibm.com/gerrit1/83418
Tested-by: Jenkins Server <pfd-jenkins+hostboot@us.ibm.com>
Reviewed-by: Brian J Stegmiller <bjs@us.ibm.com>
Reviewed-by: Benjamen G Tyner <ben.tyner@ibm.com>
Reviewed-by: Paul Greenwood <paul.greenwood@ibm.com>
Reviewed-by: Zane C Shelley <zshelle@us.ibm.com>
Reviewed-on: http://rchgit01.rchland.ibm.com/gerrit1/83419
Tested-by: Jenkins OP Build CI <op-jenkins+hostboot@us.ibm.com>
Tested-by: FSP CI Jenkins <fsp-CI-jenkins+hostboot@us.ibm.com>
Tested-by: Jenkins OP HW <op-hw-jenkins+hostboot@us.ibm.com>

src/usr/diag/prdf/plat/mem/prdfP9Mca.C

@@ -666,7 +666,7 @@ uint32_t __analyzeHealthStatus1Reg( STEP_CODE_DATA_STRUCT & io_sc,
  * @return FAIL if unable to read register, else SUCCESS
  */
 uint32_t __readTemp( TargetHandle_t i_dimm, uint16_t i_tempMsbReg,
-                     uint16_t i_tempLsbReg, uint16_t o_tempData )
+                     uint16_t i_tempLsbReg, uint16_t & o_tempData )
 {
     #define PRDF_FUNC "[__readTemp] "
 
@@ -725,7 +725,7 @@ uint32_t __readTemp( TargetHandle_t i_dimm, uint16_t i_tempMsbReg,
             break;
         }
 
-        o_tempData = (msbData << 8) | lsbData;
+        o_tempData = ((uint16_t)msbData << 8) | lsbData;
 
     }while(0);