printk() - restore timestamp printing at console output

The output of the timestamps got lost with the conversion of the
kmsg buffer to records; restore the old behavior.

Document, that CONFIG_PRINTK_TIME now only controls the output of
the timestamps in the syslog() system call and on the console, and
not the recording of the timestamps.

Cc: Joe Perches <joe@perches.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Sasha Levin <levinsasha928@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Reported-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Kay Sievers <kay@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index ef8192b..e119341 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -3,12 +3,16 @@
 	bool "Show timing information on printks"
 	depends on PRINTK
 	help
-	  Selecting this option causes timing information to be
-	  included in printk output.  This allows you to measure
-	  the interval between kernel operations, including bootup
-	  operations.  This is useful for identifying long delays
-	  in kernel startup.  Or add printk.time=1 at boot-time.
-	  See Documentation/kernel-parameters.txt
+	  Selecting this option causes time stamps of the printk()
+	  messages to be added to the output of the syslog() system
+	  call and at the console.
+
+	  The timestamp is always recorded internally, and exported
+	  to /dev/kmsg. This flag just specifies if the timestamp should
+	  be included, not that the timestamp is recorded.
+
+	  The behavior is also controlled by the kernel command line
+	  parameter printk.time=1. See Documentation/kernel-parameters.txt
 
 config DEFAULT_MESSAGE_LOGLEVEL
 	int "Default message log level (1-7)"