fpga: Export fpga_get_desc for SPL

SPL needs to detect FPGA device which will be used
for loading bitstream.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
diff --git a/drivers/fpga/fpga.c b/drivers/fpga/fpga.c
index 37946d5..d94eb5c 100644
--- a/drivers/fpga/fpga.c
+++ b/drivers/fpga/fpga.c
@@ -38,7 +38,7 @@
 /* fpga_get_desc
  *	map a device number to a descriptor
  */
-static const fpga_desc *const fpga_get_desc(int devnum)
+const fpga_desc *const fpga_get_desc(int devnum)
 {
 	fpga_desc *desc = (fpga_desc *)NULL;