MT#55283 update test for .reduce method

6.12.101+ has removed this as well. Use the macro itself to determine
whether this struct member exists.

Change-Id: Ib43157567a78afc664398b9f22ee0a27b0facfa0

kernel-module/nft_rtpengine.c

@@ -7603,7 +7603,7 @@ static const struct nft_expr_ops rtpengine_inet_ops = {
 	.destroy		= rtpengine_expr_destroy,
 	.dump			= rtpengine_expr_dump,
 	.validate		= rtpengine_expr_validate,
-#if LINUX_VERSION_CODE >= KERNEL_VERSION(5,17,0) && LINUX_VERSION_CODE < KERNEL_VERSION(7,1,0)
+#ifdef NFT_REDUCE_READONLY
 	.reduce			= NFT_REDUCE_READONLY,
 #endif
 };
@@ -7616,7 +7616,7 @@ static const struct nft_expr_ops rtpengine_ipv4_ops = {
 	.destroy		= rtpengine_expr_destroy,
 	.dump			= rtpengine_expr_dump,
 	.validate		= rtpengine_expr_validate,
-#if LINUX_VERSION_CODE >= KERNEL_VERSION(5,17,0) && LINUX_VERSION_CODE < KERNEL_VERSION(7,1,0)
+#ifdef NFT_REDUCE_READONLY
 	.reduce			= NFT_REDUCE_READONLY,
 #endif
 };
@@ -7629,7 +7629,7 @@ static const struct nft_expr_ops rtpengine_ipv6_ops = {
 	.destroy		= rtpengine_expr_destroy,
 	.dump			= rtpengine_expr_dump,
 	.validate		= rtpengine_expr_validate,
-#if LINUX_VERSION_CODE >= KERNEL_VERSION(5,17,0) && LINUX_VERSION_CODE < KERNEL_VERSION(7,1,0)
+#ifdef NFT_REDUCE_READONLY
 	.reduce			= NFT_REDUCE_READONLY,
 #endif
 };