cb710: handle DEBUG define in Makefile

Signed-off-by: Pierre Ossman <pierre@ossman.eu>
diff --git a/drivers/misc/cb710/Makefile b/drivers/misc/cb710/Makefile
index 62d51ac..7b80cbf 100644
--- a/drivers/misc/cb710/Makefile
+++ b/drivers/misc/cb710/Makefile
@@ -1,3 +1,7 @@
+ifeq ($(CONFIG_CB710_DEBUG),y)
+	EXTRA_CFLAGS		+= -DDEBUG
+endif
+
 obj-$(CONFIG_CB710_CORE)	+= cb710.o
 
 cb710-y				:= core.o sgbuf2.o