bootconfig: Remove duplicate included header file linux/bootconfig.h

The header file linux/bootconfig.h is included whether __KERNEL__ is
defined or not.

Include it only once before the #ifdef/#else/#endif preprocessor
directives and remove the following make includecheck warning:

  linux/bootconfig.h is included more than once

Move the comment to the top and delete the now empty #else block.

Link: https://lore.kernel.org/all/20240711084315.1507-1-thorsten.blum@toblux.com/Signed-off-by: Thorsten Blum <thorsten.blum@toblux.com>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>

lib/bootconfig.c

@@ -4,8 +4,16 @@
  * Masami Hiramatsu <mhiramat@kernel.org>
  */
 
-#ifdef __KERNEL__
+/*
+ * NOTE: This is only for tools/bootconfig, because tools/bootconfig will
+ * run the parser sanity test.
+ * This does NOT mean lib/bootconfig.c is available in the user space.
+ * However, if you change this file, please make sure the tools/bootconfig
+ * has no issue on building and running.
+ */
 #include <linux/bootconfig.h>
+
+#ifdef __KERNEL__
 #include <linux/bug.h>
 #include <linux/ctype.h>
 #include <linux/errno.h>
@@ -24,16 +32,6 @@ const char * __init xbc_get_embedded_bootconfig(size_t *size)
 	return (*size) ? embedded_bootconfig_data : NULL;
 }
 #endif
-
-#else /* !__KERNEL__ */
-/*
- * NOTE: This is only for tools/bootconfig, because tools/bootconfig will
- * run the parser sanity test.
- * This does NOT mean lib/bootconfig.c is available in the user space.
- * However, if you change this file, please make sure the tools/bootconfig
- * has no issue on building and running.
- */
-#include <linux/bootconfig.h>
 #endif
 
 /*