Stack cleanups (#1193)

* Use STACK and STACK_TOP everywhere

* format

* remove fake variable

* bss

* review

Co-authored-by: Derek Hensley <hensley.derek58@gmail.com>

* Update src/boot_O2_g3/boot_main.c

Co-authored-by: Derek Hensley <hensley.derek58@gmail.com>

* review

* renames

* more renames

* and more

* whoopsie, forgot those too

* hopefully the last cleanup

* forgot some stuff

* a

* bss

---------

Co-authored-by: Derek Hensley <hensley.derek58@gmail.com>

include/stack.h

@@ -0,0 +1,12 @@
+#ifndef STACK_H
+#define STACK_H
+
+#include "alignment.h"
+
+#define STACK(stack, size) \
+    u64 stack[ALIGN8(size) / sizeof(u64)]
+
+#define STACK_TOP(stack) \
+    ((u8*)(stack) + sizeof(stack))
+
+#endif