ANDROID: inline isolate_and_split_free_page

Add inline keyword to pass compilation when CONFIG_COMPACTION is not
enabled.

include/linux/compaction.h:241:22: warning: 'isolate_and_split_free_page' defined but not used [-Wunused-function]

Change-Id: I6bec2789a68e1b8fc9f4ea8f7267571a333d68ef
Fixes: commit 8cd9aa93b726 ("ANDROID: implement wrapper for reverse migration")
Bug: 175403896
Signed-off-by: Elliot Berman <eberman@codeaurora.org>
diff --git a/include/linux/compaction.h b/include/linux/compaction.h
index 8d14563..5734e3c 100644
--- a/include/linux/compaction.h
+++ b/include/linux/compaction.h
@@ -238,7 +238,7 @@ static inline void wakeup_kcompactd(pg_data_t *pgdat,
 {
 }
 
-static unsigned long isolate_and_split_free_page(struct page *page,
+static inline unsigned long isolate_and_split_free_page(struct page *page,
 				struct list_head *list)
 {
 	return 0;