pmem: Make request/release region return a value

the request_region/release_region call backs now return
an error code. This way if the request fails the allocation
can fail as well.

Change-Id: I817c65a43935fb41176ad03f5a7672fb5640084e
Signed-off-by: Laura Abbott <lauraa@codeaurora.org>
diff --git a/include/linux/android_pmem.h b/include/linux/android_pmem.h
index c029196..3c4dd79 100644
--- a/include/linux/android_pmem.h
+++ b/include/linux/android_pmem.h
@@ -157,12 +157,12 @@
 	 * function to be called when the number of allocations goes from
 	 * 0 -> 1
 	 */
-	void (*request_region)(void *);
+	int (*request_region)(void *);
 	/*
 	 * function to be called when the number of allocations goes from
 	 * 1 -> 0
 	 */
-	void (*release_region)(void *);
+	int (*release_region)(void *);
 	/*
 	 * function to be called upon pmem registration
 	 */