memory: split cpu_physical_memory_* functions to its own include

All the functions that use ram_addr_t should be here.

Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Orit Wasserman <owasserm@redhat.com>
diff --git a/exec.c b/exec.c
index 514d6a0..b387d28 100644
--- a/exec.c
+++ b/exec.c
@@ -50,6 +50,7 @@
 #include "translate-all.h"
 
 #include "exec/memory-internal.h"
+#include "exec/ram_addr.h"
 #include "qemu/cache-utils.h"
 
 #include "qemu/range.h"