Refactor: rename namespace witherspoon to phosphor

This repo now becomes phosphor-power, rename namespace witherspoon to
phosphor to make it generic.

Signed-off-by: Lei YU <mine260309@gmail.com>
Change-Id: Icb9f8a7c33065add99f2bf42ed55745a28fa0424
diff --git a/power-sequencer/ucd90160.cpp b/power-sequencer/ucd90160.cpp
index d0d176c..eaaad56 100644
--- a/power-sequencer/ucd90160.cpp
+++ b/power-sequencer/ucd90160.cpp
@@ -26,7 +26,7 @@
 #include <phosphor-logging/log.hpp>
 #include <xyz/openbmc_project/Common/Device/error.hpp>
 
-namespace witherspoon
+namespace phosphor
 {
 namespace power
 {
@@ -507,4 +507,4 @@
 }
 
 } // namespace power
-} // namespace witherspoon
+} // namespace phosphor