utils: ipu3: Fix return value check on file output

The data parsed by ipu3-unpack is written out using the write() c
library call, but the error code is incorrectly checked which misses the
single erroroneous return value returned by the function.

Fix it to explicitly check against the error code.

Fixes: 23ac77dc4a ("utils: ipu3: Add IPU3 raw capture unpack utility")
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Umang Jain <umang.jain@ideasonboard.com>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

utils/ipu3/ipu3-unpack.c

@@ -78,7 +78,7 @@ int main(int argc, char *argv[])
 		}
 
 		ret = write(out_fd, out_data, 50);
-		if (ret < -1) {
+		if (ret == -1) {
 			fprintf(stderr, "Failed to write output data: %s\n",
 				strerror(errno));
 			goto done;