[boot] Add explicit dependency on bootproto/memory.h

bootproto/memory.h is generated from a cog file. Some builds could fail
because the dependency on this file was not explicit.

src/kernel/memory.h.cog

@@ -1,7 +1,7 @@
 #pragma once
 // vim: ft=cpp
 
-/// \file bootproto/memory.h
+/// \file memory.h
 /// Import memory layout constants necessary for boot
 
 #include <stddef.h>