pio: Remove pio headers from MRAA

The Native PIO API provides both the libraries and headers for use with
the Android Things Peripheralanager client.  This commit removes these
from the MRAA repo in favor of the FindAndroidThings.cmake provided by
the Native PIO API.

Signed-off-by: Noel Eck <noel.eck@intel.com>

src/peripheralman/peripheralman.c

@@ -27,7 +27,7 @@
 #include <syslog.h>
 
 #include "mraa_internal.h"
-#include "peripheralman.h"
+#include "peripheralmanager/peripheralman.h"
 
 APeripheralManagerClient *client = NULL;
 char **gpios = NULL;