char: change to new flag variable

Replace EXTRA_CFLAGS with ccflags-y.

Signed-off-by: matt mooney <mfm@muteddisk.com>
Acked-by: WANG Cong <xiyou.wangcong@gmail.com>
Signed-off-by: Michal Marek <mmarek@suse.cz>
diff --git a/drivers/char/mwave/README b/drivers/char/mwave/README
index 480251f..c2a58f4 100644
--- a/drivers/char/mwave/README
+++ b/drivers/char/mwave/README
@@ -11,7 +11,7 @@
 	0x0008 tp3780i tracing
 
         Tracing only occurs if the driver has been compiled with the
-        MW_TRACE macro #defined  (i.e. let EXTRA_CFLAGS += -DMW_TRACE
+        MW_TRACE macro #defined  (i.e. let ccflags-y := -DMW_TRACE
         in the Makefile).
 
   mwave_3780i_irq=5/7/10/11/15