docs: correct documentation for %pK

Current documentation indicates that %pK prints a leading '0x'. This is
not the case.

Correct documentation for printk specifier %pK.
Signed-off-by: Tobin C. Harding <me@tobin.cc>

Documentation/printk-formats.txt

@@ -85,13 +85,12 @@ Examples::
 	printk("Faulted at %pS\n", (void *)regs->ip);
 	printk(" %s%pB\n", (reliable ? "" : "? "), (void *)*stack);
 
-
 Kernel Pointers
 ===============
 
 ::
 
-	%pK	0x01234567 or 0x0123456789abcdef
+	%pK	01234567 or 0123456789abcdef
 
 For printing kernel pointers which should be hidden from unprivileged
 users. The behaviour of ``%pK`` depends on the ``kptr_restrict sysctl`` - see