m68k: Return -ENODEV if no device is found

According to the tests in do_initcalls(), the proper error code in case no
device is found is -ENODEV, not -ENXIO or -EIO.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/block/z2ram.c b/drivers/block/z2ram.c
index 2d5853c..be20a67 100644
--- a/drivers/block/z2ram.c
+++ b/drivers/block/z2ram.c
@@ -332,7 +332,7 @@
     int ret;
 
     if (!MACH_IS_AMIGA)
-	return -ENXIO;
+	return -ENODEV;
 
     ret = -EBUSY;
     if (register_blkdev(Z2RAM_MAJOR, DEVICE_NAME))