move implementation to ipmi file

Move the entrance point for the IPMI OEM handling to a separate file and
pass in the handler pointer via binding.

Signed-off-by: Patrick Venture <venture@google.com>
Change-Id: I4371ebee1c252ab6e9d8a7ff2389583919ecc996
diff --git a/pcie_i2c.cpp b/pcie_i2c.cpp
index 625c063..989ef41 100644
--- a/pcie_i2c.cpp
+++ b/pcie_i2c.cpp
@@ -16,7 +16,7 @@
 
 #include "pcie_i2c.hpp"
 
-#include "main.hpp"
+#include "ipmi.hpp"
 
 #include <cstdint>
 #include <cstring>