tracing: Fix documentation on tp_printk cmdline option

kernel-parameters.txt incorrectly states that workings of
kernel.tracepoint_printk sysctl depends on "tracepoint_printk kernel
cmdline option", this is a bit misleading for new users since the actual
cmdline option name is tp_printk.

Fixes: 0daa2302 ("tracing: Add tp_printk cmdline to have tracepoints go to printk()")
Signed-off-by: Vitaly Chikunov <vt@altlinux.org>
Reviewed-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20240323231704.1217926-1-vt@altlinux.org

Documentation/admin-guide/kernel-parameters.txt

@@ -6599,7 +6599,7 @@
 			To turn off having tracepoints sent to printk,
 			 echo 0 > /proc/sys/kernel/tracepoint_printk
 			Note, echoing 1 into this file without the
-			tracepoint_printk kernel cmdline option has no effect.
+			tp_printk kernel cmdline option has no effect.
 
 			The tp_printk_stop_on_boot (see below) can also be used
 			to stop the printing of events to console at