fpga: Add flag to indicate bitstream needs decrypting

Add a flag that is passed to the write_init() callback, indicating
that the bitstream is encrypted.

The low-level driver will deal with the flag, or return an error,
if encrypted bitstreams are not supported.
Signed-off-by: Moritz Fischer <mdf@kernel.org>
Acked-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Alan Tull <atull@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

include/linux/fpga/fpga-mgr.h

@@ -70,6 +70,7 @@ enum fpga_mgr_states {
  */
 #define FPGA_MGR_PARTIAL_RECONFIG	BIT(0)
 #define FPGA_MGR_EXTERNAL_CONFIG	BIT(1)
+#define FPGA_MGR_ENCRYPTED_BITSTREAM	BIT(2)
 
 /**
  * struct fpga_image_info - information specific to a FPGA image