Description: ipv6: mcast: fix data-race in ipv6_mc_down / mld_ifc_work
References:
Notes:
 carnil> Introduced in 2d9a93b4902b ("mld: convert from timer to delayed work").
 carnil> Vulnerable versions: 5.13-rc1.
Bugs:
upstream: released (6.8-rc1) [2e7ef287f07c74985f1bf2858bedc62bd9ebf155]
6.7-upstream-stable: released (6.7.2) [3bb5849675ae1d592929798a2b37ea450879c855]
6.6-upstream-stable: released (6.6.14) [3cc283fd16fba72e2cefe3a6f48d7a36b0438900]
6.1-upstream-stable: released (6.1.75) [380540bb06bb1d1b12bdc947d1b8f56cda6b5663]
5.10-upstream-stable: N/A "Vulnerable code not present"
4.19-upstream-stable: N/A "Vulnerable code not present"
sid: released (6.6.15-1)
6.1-bookworm-security: released (6.1.76-1)
5.10-bullseye-security: N/A "Vulnerable code not present"
4.19-buster-security: N/A "Vulnerable code not present"