[includes] remove lk/utils.h which seem to be unused on anything in mainline

Was a bit of a hodgepodge of defines. If any of these are needed we can
add them back somewhere a bit more appropriate.

ARRAY_SIZE can use countof() defined in compiler.h

KB/MB/GB are generally duplicately defined in architecture specific
files, but not generically. I couldn't think off the top of my head of a
better place to generically put these, especially since they're used in
asm files, so just deleted it for now.

The other stuff seemed to be just unused anywhere.

top/include/lk/utils.h

@@ -1,21 +0,0 @@
-/*
- * SPDX-License-Identifier: MIT
- *
- * Copyright (C) 2020-2023 Google LLC.
- */
-
-#pragma once
-
-#define ARRAY_SIZE(_a) (sizeof(_a) / sizeof(*(_a)))
-
-#define KB (1024UL)
-#define MB (1024UL * 1024UL)
-#define GB (1024UL * 1024UL * 1024UL)
-
-#define RETURN_IF_ERROR(expr) \
-        do { \
-            status_t err_ = (expr); \
-            if (err_ != NO_ERROR) { \
-                return err_; \
-            } \
-        } while (0)