linux: use correct conditional for wireguard kernel config fixup

Commit de591c5c3a93 (package/wireguard-linux-compat: new package) split up
the wireguard package in wireguard-tools and wireguard-linux-compat, but
forgot to update the conditional in linux.mk, so the kernel config fixups
needed for wireguard are no longer applied.

Update the conditional to use the BR2_PACKAGE_WIREGUARD_LINUX_COMPAT symbol
instead.

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

linux/linux.mk

@@ -392,7 +392,7 @@ define LINUX_KCONFIG_FIXUP_CMDS
 		$(call KCONFIG_ENABLE_OPT,CONFIG_NF_CONNTRACK,$(@D)/.config)
 		$(call KCONFIG_ENABLE_OPT,CONFIG_NF_CONNTRACK_MARK,$(@D)/.config)
 		$(call KCONFIG_ENABLE_OPT,CONFIG_NF_NAT,$(@D)/.config))
-	$(if $(BR2_PACKAGE_WIREGUARD),
+	$(if $(BR2_PACKAGE_WIREGUARD_LINUX_COMPAT),
 		$(call KCONFIG_ENABLE_OPT,CONFIG_INET,$(@D)/.config)
 		$(call KCONFIG_ENABLE_OPT,CONFIG_NET,$(@D)/.config)
 		$(call KCONFIG_ENABLE_OPT,CONFIG_NET_FOU,$(@D)/.config)