mtd: m25p80: remove 'disabled' device check

It seems like the following commit was never necessary

    commit 5f949137952020214cd167093dd7be448f21c079
    Author: Shaohui Xie <Shaohui.Xie@freescale.com>
    Date:   Fri Oct 14 15:49:00 2011 +0800

        mtd: m25p80: don't probe device which has status of 'disabled'

because it duplicates the code in of_platform_device_create_pdata()
which ensures that 'disabled' nodes are never instantiated.

Also, drop the __maybe_unused.

Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Reviewed-by: Sourav Poddar <sourav.poddar@ti.com>
Reviewed-by: Grant Likely <grant.likely@linaro.org>
Cc: Rob Herring <rob.herring@calxeda.com>
Cc: <devicetree@vger.kernel.org>

drivers/mtd/devices/m25p80.c

@@ -935,12 +935,7 @@ static int m25p_probe(struct spi_device *spi)
 	struct flash_info		*info;
 	unsigned			i;
 	struct mtd_part_parser_data	ppdata;
-	struct device_node __maybe_unused *np = spi->dev.of_node;
-
-#ifdef CONFIG_MTD_OF_PARTS
-	if (!of_device_is_available(np))
-		return -ENODEV;
-#endif
+	struct device_node *np = spi->dev.of_node;
 
 	/* Platform data helps sort out which chip type we have, as
 	 * well as how this board partitions it.  If we don't have