vfio-mdev: Fix mtty sample driver building

This sample driver was originally under Documentation/ and was moved
to samples, but build support was never adjusted for the new location.
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Tested-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Kirti Wankhede <kwankhede@nvidia.com>

samples/Kconfig

@@ -105,4 +105,11 @@ config SAMPLE_BLACKFIN_GPTIMERS
 	help
 	  Build samples of blackfin gptimers sample module.
 
+config SAMPLE_VFIO_MDEV_MTTY
+	tristate "Build VFIO mtty example mediated device sample code -- loadable modules only"
+	depends on VFIO_MDEV_DEVICE && m
+	help
+	  Build a virtual tty sample driver for use as a VFIO
+	  mediated device
+
 endif # SAMPLES

samples/Makefile

@@ -2,4 +2,5 @@
 
 obj-$(CONFIG_SAMPLES)	+= kobject/ kprobes/ trace_events/ livepatch/ \
 			   hw_breakpoint/ kfifo/ kdb/ hidraw/ rpmsg/ seccomp/ \
-			   configfs/ connector/ v4l/ trace_printk/ blackfin/
+			   configfs/ connector/ v4l/ trace_printk/ blackfin/ \
+			   vfio-mdev/

samples/vfio-mdev/Makefile

-#
-# Makefile for mtty.c file
-#
-KERNEL_DIR:=/lib/modules/$(shell uname -r)/build
-
-obj-m:=mtty.o
-
-modules clean modules_install:
-	$(MAKE) -C $(KERNEL_DIR) SUBDIRS=$(PWD) $@
-
-default: modules
-
-module: modules
+obj-$(CONFIG_SAMPLE_VFIO_MDEV_MTTY) += mtty.o