fpga: fpga-mgr: xilinx-spi: fix error messages on -EPROBE_DEFER

The current code produces an error message on devm_gpiod_get() errors even
when the error is -EPROBE_DEFER, which should be silent.

This has been observed producing a significant amount of messages like:

    xlnx-slave-spi spi1.1: Failed to get PROGRAM_B gpio: -517

Fix and simplify code by using the dev_err_probe() helper function.
Signed-off-by: Luca Ceresoli <luca@lucaceresoli.net>
Fixes: dd2784c0 ("fpga manager: xilinx-spi: check INIT_B pin during write_init")
Fixes: 061c97d1 ("fpga manager: Add Xilinx slave serial SPI driver")
Signed-off-by: Moritz Fischer <mdf@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/fpga/xilinx-spi.c

@@ -233,25 +233,19 @@ static int xilinx_spi_probe(struct spi_device *spi)
 
 	/* PROGRAM_B is active low */
 	conf->prog_b = devm_gpiod_get(&spi->dev, "prog_b", GPIOD_OUT_LOW);
-	if (IS_ERR(conf->prog_b)) {
-		dev_err(&spi->dev, "Failed to get PROGRAM_B gpio: %ld\n",
-			PTR_ERR(conf->prog_b));
-		return PTR_ERR(conf->prog_b);
-	}
+	if (IS_ERR(conf->prog_b))
+		return dev_err_probe(&spi->dev, PTR_ERR(conf->prog_b),
+				     "Failed to get PROGRAM_B gpio\n");
 
 	conf->init_b = devm_gpiod_get_optional(&spi->dev, "init-b", GPIOD_IN);
-	if (IS_ERR(conf->init_b)) {
-		dev_err(&spi->dev, "Failed to get INIT_B gpio: %ld\n",
-			PTR_ERR(conf->init_b));
-		return PTR_ERR(conf->init_b);
-	}
+	if (IS_ERR(conf->init_b))
+		return dev_err_probe(&spi->dev, PTR_ERR(conf->init_b),
+				     "Failed to get INIT_B gpio\n");
 
 	conf->done = devm_gpiod_get(&spi->dev, "done", GPIOD_IN);
-	if (IS_ERR(conf->done)) {
-		dev_err(&spi->dev, "Failed to get DONE gpio: %ld\n",
-			PTR_ERR(conf->done));
-		return PTR_ERR(conf->done);
-	}
+	if (IS_ERR(conf->done))
+		return dev_err_probe(&spi->dev, PTR_ERR(conf->done),
+				     "Failed to get DONE gpio\n");
 
 	mgr = devm_fpga_mgr_create(&spi->dev,
 				   "Xilinx Slave Serial FPGA Manager",