Move policy_engine.h to lib/src/

To do this, a couple of the events had to have their definitions moved
to lib/include/pdb_pe.h.  This isn't a problem in and of itself, but if
more internal-use events are added to policy_engine.h there could be
trouble.  To mitigate this, I added a comment as a reminder to make sure
any new events don't overlap the public ones defined elsewhere.

lib/include/pdb_pe.h

 
 #include <ch.h>
 
+/*
+ * Events for the Policy Engine thread, sent by user code
+ */
+/* Tell the PE to send a Get_Source_Cap message */
+#define PDB_EVT_PE_GET_SOURCE_CAP EVENT_MASK(6)
+/* Tell the PE that new power is required */
+#define PDB_EVT_PE_NEW_POWER EVENT_MASK(7)
+
 
+/*
+ * Structure for Policy Engine thread and variables
+ */
 struct pdb_pe {
     THD_WORKING_AREA(_wa, 256);
     thread_t *thread;

lib/include/policy_engine.h → lib/src/policy_engine.h

 
 #include <pdb.h>
 
-
-/* Events for the Policy Engine thread */
+/*
+ * Events for the Policy Engine thread, used internally
+ *
+ * NOTE: If any more events are needed, make sure they don't overlap the ones
+ * in include/pdb_pe.h!
+ */
 #define PDB_EVT_PE_RESET EVENT_MASK(0)
 #define PDB_EVT_PE_MSG_RX EVENT_MASK(1)
 #define PDB_EVT_PE_TX_DONE EVENT_MASK(2)
 #define PDB_EVT_PE_TX_ERR EVENT_MASK(3)
 #define PDB_EVT_PE_HARD_SENT EVENT_MASK(4)
 #define PDB_EVT_PE_I_OVRTEMP EVENT_MASK(5)
-#define PDB_EVT_PE_GET_SOURCE_CAP EVENT_MASK(6)
-#define PDB_EVT_PE_NEW_POWER EVENT_MASK(7)
+
 
 /*
  * Start the Policy Engine thread

src/shell.c

 
 #include "chprintf.h"
 
+#include <pdb.h>
 #include "usbcfg.h"
 #include "config.h"
 #include "led.h"
 #include "device_policy_manager.h"
-#include "policy_engine.h"
 #include "pd.h"