fpga: Change the first parameter in fpga_loadbitstream

All fpga functions use devnum as int. Only fpga_loadbitstream
is using it as unsinged long dev.
This patch synchronize it.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Reviewed-by: Tom Rini <trini@ti.com>

drivers/fpga/fpga.c

@@ -190,7 +190,7 @@ int fpga_add(fpga_type devtype, void *desc)
 /*
  * Convert bitstream data and load into the fpga
  */
-int __weak fpga_loadbitstream(unsigned long dev, char *fpgadata, size_t size)
+int __weak fpga_loadbitstream(int devnum, char *fpgadata, size_t size)
 {
 	printf("Bitstream support not implemented for this FPGA device\n");
 	return FPGA_FAIL;