[NETFILTER]: Update modules' descriptions

Updates the MODULE_DESCRIPTION() tags for all Netfilter modules,
actually describing what the module does and not just
"netfilter XYZ target".

Signed-off-by: Jan Engelhardt <[email protected]>
Signed-off-by: Patrick McHardy <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
67 files changed