CVE-2025-40168 smc: Use __sk_dst_get() and dst_dev_rcu() in smc_clc_prfx_match().

In the Linux kernel, the following vulnerability has been resolved: smc: Use skdstget and dstdevrcu in smcclcprfxmatch. smcclcprfxmatch is called from smclistenwork and not under RCU nor RTNL. Using skdstgetsk-dev could trigger UAF. Let's use skdstget and dstdevrcu. Note that the returned value o...