add printk.time option, deprecate 'time'

Allow printk_time to be enabled or disabled at boot time.  Previously it
could be enabled only, but not disabled.

Change printk_time from an int to a bool since that's what it is.  Make its
logical (exposed) name just be "time" (was "printk_time").

Note: Changes kernel boot option syntax from "time" to "printk.time=value".

Since printk_time is declared as a module_param, it can also be
changed at run-time by modifying
  /sys/module/printk/parameters/time
to a value of 1/Y/y to enabled it or 0/N/n to disable it.

Since printk_time is declared as a module_param, its value can also
be set at boot-time by using
  linux printk.time=<bool>

If the "time" boot option is used, print a message that it is deprecated
and will be removed.

Note its planned removal in feature-removal-schedule.txt.

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index ab38322..a0362d5 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1389,6 +1389,9 @@
 			the kernel console.
 			default: off.
 
+	printk.time=	Show timing data prefixed to each printk message line
+			Format: <bool>  (1/Y/y=enable, 0/N/n=disable)
+
 	profile=	[KNL] Enable kernel profiling via /proc/profile
 			Format: [schedule,]<number>
 			Param: "schedule" - profile schedule points.
@@ -1824,6 +1827,7 @@
 			Set number of hash buckets for TCP connection
 
 	time		Show timing data prefixed to each printk message line
+			[deprecated, see 'printk.time']
 
 	tipar.timeout=	[HW,PPT]
 			Set communications timeout in tenths of a second