Makefile: Documentation for external tool should be correct

If one includes documentation for an external tool, it should be
correct.  This is not:

1. Overriding the input to rngd should typically be neither
   necessary nor desired.  This is especially so since newer
   versions of rngd support a number of different *types* of sources.
2. The default kernel-exported device is called /dev/hwrng not
   /dev/hwrandom nor /dev/hw_random (both of which were used in the
   past; however, kernel and udev seem to have converged on
   /dev/hwrng.)

Overall it is better if the documentation for rngd is kept with rngd
rather than in a kernel Makefile.
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Jeff Garzik <jgarzik@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kernel/Makefile

@@ -174,10 +174,8 @@ signing_key.priv signing_key.x509: x509.genkey
 	@echo "###"
 	@echo "### If this takes a long time, you might wish to run rngd in the"
 	@echo "### background to keep the supply of entropy topped up.  It"
-	@echo "### needs to be run as root, and should use a hardware random"
-	@echo "### number generator if one is available, eg:"
-	@echo "###"
-	@echo "###     rngd -r /dev/hwrandom"
+	@echo "### needs to be run as root, and uses a hardware random"
+	@echo "### number generator if one is available."
 	@echo "###"
 	openssl req -new -nodes -utf8 $(sign_key_with_hash) -days 36500 -batch \
 		-x509 -config x509.genkey \