fix:memory:of_memory:add missing header dependencies

We get 2 warnings when biuld kernel with W=1:
drivers/memory/of_memory.c:30:30: warning: no previous prototype for 'of_get_min_tck' [-Wmissing-prototypes]
drivers/memory/of_memory.c:106:30: warning: no previous prototype for 'of_get_ddr_timings' [-Wmissing-prototypes]

In fact, these functions are declared in drivers/memory/of_memory.h
so this patch add missing header dependencies.
Signed-off-by: Baoyou Xie <baoyou.xie@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/memory/of_memory.c

@@ -16,6 +16,7 @@
 #include <linux/gfp.h>
 #include <memory/jedec_ddr.h>
 #include <linux/export.h>
+#include "of_memory.h"
 
 /**
  * of_get_min_tck() - extract min timing values for ddr