Revert "ipv4: Clarify in docs that accept_local requires rp_filter."

This reverts commit c801e3cc1925 ("ipv4: Clarify in docs that accept_local requires rp_filter.").
It is not needed anymore since commit 1dced6a85482 ("ipv4: Restore accept_local behaviour in fib_validate_source()").

Suggested-by: Julian Anastasov <ja@ssi.bg>
Cc: Gregory Detal <gregory.detal@uclouvain.be>
Cc: Christoph Paasch <christoph.paasch@uclouvain.be>
Cc: Hannes Frederic Sowa <hannes@redhat.com>
Cc: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Signed-off-by: Sébastien Barré <sebastien.barre@uclouvain.be>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/networking/ip-sysctl.txt

@@ -952,14 +952,9 @@ accept_source_route - BOOLEAN
 		FALSE (host)
 
 accept_local - BOOLEAN
-	Accept packets with local source addresses. In combination
-	with suitable routing, this can be used to direct packets
-	between two local interfaces over the wire and have them
-	accepted properly.
-
-	rp_filter must be set to a non-zero value in order for
-	accept_local to have an effect.
-
+	Accept packets with local source addresses. In combination with
+	suitable routing, this can be used to direct packets between two
+	local interfaces over the wire and have them accepted properly.
 	default FALSE
 
 route_localnet - BOOLEAN