fpga: Add bitstream type BIT_NONE

Add bitstream type BIT_NONE to the bitstream type
enum. This might be useful while loading bitstreams
in respective drivers.

Signed-off-by: Siva Durga Prasad Paladugu <sivadur@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
diff --git a/include/fpga.h b/include/fpga.h
index e0d1298..d768fb1 100644
--- a/include/fpga.h
+++ b/include/fpga.h
@@ -46,6 +46,7 @@
 typedef enum {
 	BIT_FULL = 0,
 	BIT_PARTIAL,
+	BIT_NONE = 0xFF,
 } bitstream_type;
 
 /* root function definitions */