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
(cherry picked from commit 83b05e9a11)
(cherry picked from commit ca1ed34d35)

kernel-module/nft_rtpengine.c

@@ -7433,7 +7433,7 @@ static const struct nft_expr_ops rtpengine_inet_ops = {
 	.init			= rtpengine_expr_init,
 	.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
 };
@@ -7445,7 +7445,7 @@ static const struct nft_expr_ops rtpengine_ipv4_ops = {
 	.init			= rtpengine_expr_init,
 	.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
 };
@@ -7457,7 +7457,7 @@ static const struct nft_expr_ops rtpengine_ipv6_ops = {
 	.init			= rtpengine_expr_init,
 	.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
 };