staging: android: ion: mark symbols static where possible

We get 4 warnings when building kernel with W=1:
drivers/staging/android/ion/ion_carveout_heap.c:36:17: warning: no previous prototype for 'ion_carveout_allocate' [-Wmissing-prototypes]
drivers/staging/android/ion/ion_carveout_heap.c:50:6: warning: no previous prototype for 'ion_carveout_free' [-Wmissing-prototypes]
drivers/staging/android/ion/ion_of.c:28:5: warning: no previous prototype for 'ion_parse_dt_heap_common' [-Wmissing-prototypes]
drivers/staging/android/ion/ion_of.c:54:5: warning: no previous prototype for 'ion_setup_heap_common' [-Wmissing-prototypes]

In fact, these functions are only used in the file in which they are
declared and don't need a declaration, but can be made static.
so this patch marks these functions with 'static'.
Signed-off-by: NBaoyou Xie <baoyou.xie@linaro.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/android/ion/ion_carveout_heap.c

@@ -33,9 +33,9 @@ struct ion_carveout_heap {
 	ion_phys_addr_t base;
 };
 
-ion_phys_addr_t ion_carveout_allocate(struct ion_heap *heap,
-				      unsigned long size,
-				      unsigned long align)
+static ion_phys_addr_t ion_carveout_allocate(struct ion_heap *heap,
+					     unsigned long size,
+					     unsigned long align)
 {
 	struct ion_carveout_heap *carveout_heap =
 		container_of(heap, struct ion_carveout_heap, heap);
@@ -47,8 +47,8 @@ ion_phys_addr_t ion_carveout_allocate(struct ion_heap *heap,
 	return offset;
 }
 
-void ion_carveout_free(struct ion_heap *heap, ion_phys_addr_t addr,
-		       unsigned long size)
+static void ion_carveout_free(struct ion_heap *heap, ion_phys_addr_t addr,
+			      unsigned long size)
 {
 	struct ion_carveout_heap *carveout_heap =
 		container_of(heap, struct ion_carveout_heap, heap);

drivers/staging/android/ion/ion_of.c

@@ -25,9 +25,9 @@
 #include "ion_priv.h"
 #include "ion_of.h"
 
-int ion_parse_dt_heap_common(struct device_node *heap_node,
-			struct ion_platform_heap *heap,
-			struct ion_of_heap *compatible)
+static int ion_parse_dt_heap_common(struct device_node *heap_node,
+				    struct ion_platform_heap *heap,
+				    struct ion_of_heap *compatible)
 {
 	int i;
 
@@ -51,9 +51,9 @@ int ion_parse_dt_heap_common(struct device_node *heap_node,
 	return 0;
 }
 
-int ion_setup_heap_common(struct platform_device *parent,
-			struct device_node *heap_node,
-			struct ion_platform_heap *heap)
+static int ion_setup_heap_common(struct platform_device *parent,
+				 struct device_node *heap_node,
+				 struct ion_platform_heap *heap)
 {
 	int ret = 0;