printk-formats.txt: remove unimplemented %pT

%pT for task->comm has been proposed (several times, I think), but is
not actually implemented.  Remove it from printk-formats.txt and add it
back if/when it gets implemented.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Documentation/printk-formats.txt

@@ -306,15 +306,6 @@ Network device features:
 
 	Passed by reference.
 
-Command from struct task_struct
-
-	%pT	ls
-
-	For printing executable name excluding path from struct
-	task_struct.
-
-	Passed by reference.
-
 If you add other %p extensions, please extend lib/test_printf.c with
 one or more test cases, if at all feasible.