ion: fix unmapped heap test settings **not for mainline**

If one enables ION_DUMMY_UNMAPPED_HEAP without providing the target
unmapped heap configuration settings (physical base address and size),
the kernel cannot build. This situation occurs in Linux test build
cases, i.e running the allmodconfig configuration.

This change overcomes the issue by providing default null settings for
both ION_DUMMY_UNMAPPED_BASE and ION_DUMMY_UNMAPPED_SIZE.

Signed-off-by: Etienne Carriere <etienne.carriere@linaro.org>
Acked-by: Jens Wiklander <jens.wiklander@linaro.org>
(cherry picked from commit ac0c2c26b9819c5e95d56cb2d8937de0357eecaa
 linaro repo https://github.com/linaro-swg/linux.git
 tag optee-v4.9-20171005)

(cherry picked from commit 533987a37a218309a49f0ad292402f91b6abf76a)
diff --git a/drivers/staging/android/ion/Kconfig b/drivers/staging/android/ion/Kconfig
index 4c26316..821871d 100644
--- a/drivers/staging/android/ion/Kconfig
+++ b/drivers/staging/android/ion/Kconfig
@@ -71,6 +71,7 @@
 config ION_DUMMY_UNMAPPED_BASE
 	hex "Physical base address of the ION unmapped heap"
 	depends on ION_DUMMY_UNMAPPED_HEAP
+	default 0
 	help
 	  Allows one the statically define an unmapped heap from the
 	  ION dummy driver to exercice unamped heaps buffer managment.
@@ -78,6 +79,7 @@
 config ION_DUMMY_UNMAPPED_SIZE
 	hex "Physical byte size of the ION unmapped heap"
 	depends on ION_DUMMY_UNMAPPED_HEAP
+	default 0
 	help
 	  Allows one the statically define an unmapped heap from the
 	  ION dummy driver to exercice unamped heaps buffer managment.
diff --git a/drivers/staging/android/ion/ion_dummy_driver.c b/drivers/staging/android/ion/ion_dummy_driver.c
index c39009a..504c379 100644
--- a/drivers/staging/android/ion/ion_dummy_driver.c
+++ b/drivers/staging/android/ion/ion_dummy_driver.c
@@ -56,7 +56,7 @@
 			.align	= SZ_16K,
 			.priv	= (void *)(SZ_16K),
 		},
-#ifdef CONFIG_ION_DUMMY_UNMAPPED_HEAP
+#if defined(CONFIG_ION_DUMMY_UNMAPPED_HEAP) && CONFIG_ION_DUMMY_UNMAPPED_SIZE
 		{
 			.id	= ION_HEAP_TYPE_UNMAPPED,
 			.type	= ION_HEAP_TYPE_UNMAPPED,