Fix implicit includes and follow c++ style cast

Change-Id: Icb2c9aa22b756e65a7969c1deecab65289f328ec
Signed-off-by: Brandon Kim <brandonkim@google.com>
diff --git a/nvme_manager.cpp b/nvme_manager.cpp
index 9ceed7c..ccd2b60 100644
--- a/nvme_manager.cpp
+++ b/nvme_manager.cpp
@@ -218,7 +218,7 @@
     nvmeData.smartWarnings = "";
     nvmeData.statusFlags = "";
     nvmeData.driveLifeUsed = "";
-    nvmeData.sensorValue = (int8_t)TEMPERATURE_SENSOR_FAILURE;
+    nvmeData.sensorValue = static_cast<int8_t>(TEMPERATURE_SENSOR_FAILURE);
     nvmeData.wcTemp = 0;
 
     phosphor::smbus::Smbus smbus;