tracing: Fix trace_buf_size boot option

We should be able to specify [KMG] when setting trace_buf_size
boot option, as documented in kernel-parameters.txt

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <4A41F2DB.4020102@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 92e1ab8..d3f41db 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -2475,7 +2475,8 @@
 
 	tp720=		[HW,PS2]
 
-	trace_buf_size=nn[KMG] [ftrace] will set tracing buffer size.
+	trace_buf_size=nn[KMG]
+			[FTRACE] will set tracing buffer size.
 
 	trix=		[HW,OSS] MediaTrix AudioTrix Pro
 			Format: