kabi: fix build error when CONFIG_KABI_RESERVE=n

hulk inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I4T1NF
CVE: NA

-------------------------------------------------

When CONFIG_KABI_RESERVE=n && CONFIG_KABI_SIZE_ALIGN_CHECKS=y, with kabi
reserved padding replaced by KABI_USE(), we will get the build error:

include/linux/kabi.h:383:3: error: static assertion failed: \
	"include/linux/fs.h:2306: long aaa is larger than . \
	Disable CONFIG_KABI_SIZE_ALIGN_CHECKS if debugging."
   _Static_assert(sizeof(struct{_new;}) <= sizeof(struct{_orig;}), \
   ^~~~~~~~~~~~~~

In fact, the result of KABI_USE() when CONFIG_KABI_RESERVE=n is weird,
update _KABI_REPLACE() to fix this.
Signed-off-by: NWei Li <liwei391@huawei.com>
Reviewed-by: NXie XiuQi <xiexiuqi@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

include/linux/kabi.h

@@ -396,6 +396,7 @@
 # define _KABI_DEPRECATE(_type, _orig)	_type kabi_reserved_##_orig
 # define _KABI_DEPRECATE_FN(_type, _orig, _args...)  \
 	_type (* kabi_reserved_##_orig)(_args)
+#ifdef CONFIG_KABI_RESERVE
 # define _KABI_REPLACE(_orig, _new)			  \
 	union {						  \
 		_new;					  \
@@ -404,6 +405,9 @@
 		} __UNIQUE_ID(kabi_hide);		  \
 		__KABI_CHECK_SIZE_ALIGN(_orig, _new);  \
 	}
+#else
+# define _KABI_REPLACE(_orig, _new)		KABI_BROKEN_REPLACE(_orig, _new)
+#endif
 
 # define _KABI_EXCLUDE(_elem)		_elem
 
@@ -426,9 +430,9 @@
  * code.
  */
 #ifdef CONFIG_KABI_RESERVE
-	# define _KABI_RESERVE(n)		u64 kabi_reserved##n
+# define _KABI_RESERVE(n)		u64 kabi_reserved##n
 #else
-	# define _KABI_RESERVE(n)
+# define _KABI_RESERVE(n)
 #endif
 # define KABI_RESERVE(n)		_KABI_RESERVE(n);
 /*