xen: add an "highmem" parameter to alloc_xenballooned_pages

Add an highmem parameter to alloc_xenballooned_pages, to allow callers to
request lowmem or highmem pages.

Fix the code style of free_xenballooned_pages' prototype.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
diff --git a/include/xen/balloon.h b/include/xen/balloon.h
index 76f7538..d29c153 100644
--- a/include/xen/balloon.h
+++ b/include/xen/balloon.h
@@ -25,8 +25,9 @@
 
 void balloon_set_new_target(unsigned long target);
 
-int alloc_xenballooned_pages(int nr_pages, struct page** pages);
-void free_xenballooned_pages(int nr_pages, struct page** pages);
+int alloc_xenballooned_pages(int nr_pages, struct page **pages,
+		bool highmem);
+void free_xenballooned_pages(int nr_pages, struct page **pages);
 
 struct sys_device;
 #ifdef CONFIG_XEN_SELFBALLOONING