gpu: ion: Add callbacks to enable SMI voting in ION.

This change is part of the move from PMEM to ION. ION needs an SMI
voting interface smiliar to PMEM's.

Change-Id: I18888f46198848694fb7e1e0d2671074bf51d7c9
Signed-off-by: Alex Bird <alexbird@codeaurora.org>
diff --git a/include/linux/ion.h b/include/linux/ion.h
index 89ac992..a7f3de5 100644
--- a/include/linux/ion.h
+++ b/include/linux/ion.h
@@ -99,6 +99,11 @@
  * @name:	used for debug purposes
  * @base:	base address of heap in physical memory if applicable
  * @size:	size of the heap in bytes if applicable
+ * @request_region: function to be called when the number of allocations goes
+ *						from 0 -> 1
+ * @release_region: function to be called when the number of allocations goes
+ *						from 1 -> 0
+ * @setup_region:   function to be called upon ion registration
  *
  * Provided by the board file.
  */
@@ -109,6 +114,9 @@
 	ion_phys_addr_t base;
 	size_t size;
 	enum ion_memory_types memory_type;
+	void (*request_region)(void *);
+	void (*release_region)(void *);
+	void *(*setup_region)(void);
 };
 
 /**