PEL: Get BCD time from epoch milliseconds

Add a new BCD time conversion function which will be used in a future
commit to convert an OpenBMC event log timestamp into BCD time.

Signed-off-by: Matt Spinler <spinler@us.ibm.com>
Change-Id: I08f585d1663bf2d2f73d42b8716756d8c7e3559e
diff --git a/extensions/openpower-pels/bcd_time.hpp b/extensions/openpower-pels/bcd_time.hpp
index e218756..86d9f4e 100644
--- a/extensions/openpower-pels/bcd_time.hpp
+++ b/extensions/openpower-pels/bcd_time.hpp
@@ -36,6 +36,14 @@
 BCDTime getBCDTime(std::chrono::time_point<std::chrono::system_clock>& time);
 
 /**
+ * @brief Converts the number of milliseconds since the epoch into BCD time
+ *
+ * @param[in] milliseconds - Number of milliseconds since the epoch
+ * @return BCDTime - the BCD time
+ */
+BCDTime getBCDTime(uint64_t milliseconds);
+
+/**
  * @brief Converts a number to a BCD.
  *
  * For example 32 -> 0x32.