staging: gs_fpgaboot: fix a compiler warning with make W=2

The below warning is fixed:

drivers/staging/gs_fpgaboot/gs_fpgaboot.c: In function ‘gs_load_image’:
drivers/staging/gs_fpgaboot/gs_fpgaboot.c:196:58: warning: declaration of ‘file’ shadows a global declaration [-Wshadow]
drivers/staging/gs_fpgaboot/gs_fpgaboot.c:45:14: warning: shadowed declaration is here [-Wshadow]

by renaming file function argument of gs_load_image with fw_file.
Signed-off-by: Devendra Naga <devendranaga4@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/gs_fpgaboot/gs_fpgaboot.c

@@ -172,15 +172,15 @@ static int gs_read_image(struct fpgaimage *fimage)
 	return 0;
 }
 
-static int gs_load_image(struct fpgaimage *fimage, char *file)
+static int gs_load_image(struct fpgaimage *fimage, char *fw_file)
 {
 	int err;
 
-	pr_info("load fpgaimage %s\n", file);
+	pr_info("load fpgaimage %s\n", fw_file);
 
-	err = request_firmware(&fimage->fw_entry, file, &firmware_pdev->dev);
+	err = request_firmware(&fimage->fw_entry, fw_file, &firmware_pdev->dev);
 	if (err != 0) {
-		pr_err("firmware %s is missing, cannot continue.\n", file);
+		pr_err("firmware %s is missing, cannot continue.\n", fw_file);
 		return err;
 	}