bootconfig: Fix the kerneldoc of _xbc_exit()

Fix the kerneldoc of _xbc_exit() which is updated to have an @early
argument and the function name is changed.

Link: https://lore.kernel.org/all/171321744474.599864.13532445969528690358.stgit@devnote2/Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202404150036.kPJ3HEFA-lkp@intel.com/
Fixes: 89f9a1e8 ("bootconfig: use memblock_free_late to free xbc memory to buddy")
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>

lib/bootconfig.c

@@ -901,7 +901,8 @@ static int __init xbc_parse_tree(void)
 }
 
 /**
- * xbc_exit() - Clean up all parsed bootconfig
+ * _xbc_exit() - Clean up all parsed bootconfig
+ * @early: Set true if this is called before budy system is initialized.
  *
  * This clears all data structures of parsed bootconfig on memory.
  * If you need to reuse xbc_init() with new boot config, you can