tools include uapi: Sync linux/if_link.h copy with the kernel sources

tools include uapi: Sync linux/if_link.h copy with the kernel sources

To pick the changes from:

  a8e3e9812935 ("net: bridge: add support for user-controlled bool options")
  63982a50fb43 ("geneve: Allow configuration of DF behaviour")
  56d9b2aa7ca3 ("vxlan: Allow configuration of DF behaviour")

Silencing this tools/ build warning:

  Warning: Kernel ABI header at 'tools/include/uapi/linux/if_link.h' differs from latest version at 'include/uapi/linux/if_link.h'

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Cc: Stefano Brivio <sbrivio@redhat.com>
Link: https://lkml.kernel.org/n/tip-wq410s2wuqv5k980bidw0ju8@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>