ram: Export last_ram_offset()

Is the only way of knowing the RAM size.

Signed-off-by: Juan Quintela <quintela@redhat.com>

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/exec.c b/exec.c
index 7899042..e63ad0d 100644
--- a/exec.c
+++ b/exec.c
@@ -2454,7 +2454,7 @@
     return offset;
 }
 
-static ram_addr_t last_ram_offset(void)
+ram_addr_t last_ram_offset(void)
 {
     RAMBlock *block;
     ram_addr_t last = 0;