Staging: iio: Don't build on s390

The IIO core expects request_irq to work, which doesn't appear to exist
on s390.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/iio/Kconfig

@@ -4,6 +4,7 @@
 
 menuconfig IIO
 	tristate "Industrial I/O support"
+	depends on !S390
 	---help---
 	  The industrial I/O subsystem provides a unified framework for
 	  drivers for many different types of embedded sensors using a