memstick: change to new flag variable

The EXTRA_CFLAGS assignment in memstick/Makefile was not accomplishing
anything because this flag only has effect on sources at the same level
as the makefile (i.e., per directory). Since both core/ and host/ rely
on MEMSTICK_DEBUG, the subdir-ccflags-y variant seems to be the
appropriate choice.

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/memstick/Makefile b/drivers/memstick/Makefile
index dc160fb4..9862359 100644
--- a/drivers/memstick/Makefile
+++ b/drivers/memstick/Makefile
@@ -2,9 +2,7 @@
 # Makefile for the kernel MemoryStick device drivers.
 #
 
-ifeq ($(CONFIG_MEMSTICK_DEBUG),y)
-	EXTRA_CFLAGS		+= -DDEBUG
-endif
+subdir-ccflags-$(CONFIG_MEMSTICK_DEBUG) := -DDEBUG
 
 obj-$(CONFIG_MEMSTICK)		+= core/
 obj-$(CONFIG_MEMSTICK)		+= host/