Fix documentation of panic_on_warn

The kernel cmdline option panic_on_warn expects an integer, it is not a
plain option as documented. A number of uses in the tree figured this
already, and use panic_on_warn=1 for their purpose.

Adjust a comment which otherwise may mislead people in the future.

Fixes: 9e3961a0 ("kernel: add panic_on_warn")
Signed-off-by: Olaf Hering <olaf@aepfle.de>
Reviewed-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/admin-guide/kernel-parameters.txt

@@ -4064,7 +4064,7 @@
 			extra details on the taint flags that users can pick
 			to compose the bitmask to assign to panic_on_taint.
 
-	panic_on_warn	panic() instead of WARN().  Useful to cause kdump
+	panic_on_warn=1	panic() instead of WARN().  Useful to cause kdump
 			on a WARN().
 
 	parkbd.port=	[HW] Parallel port number the keyboard adapter is

tools/testing/selftests/rcutorture/bin/kvm.sh

@@ -655,4 +655,4 @@ fi
 # Control buffer size: --bootargs trace_buf_size=3k
 # Get trace-buffer dumps on all oopses: --bootargs ftrace_dump_on_oops
 # Ditto, but dump only the oopsing CPU: --bootargs ftrace_dump_on_oops=orig_cpu
-# Heavy-handed way to also dump on warnings: --bootargs panic_on_warn
+# Heavy-handed way to also dump on warnings: --bootargs panic_on_warn=1