zram/xvmalloc: create CONFIG_ZRAM_DEBUG for debug code

Add a debug config flag to enable debug printk output and future
debug code.

Signed-off-by: Robert Jennings <rcj@linux.vnet.ibm.com>
Reviewed-by: Pekka Enberg <penberg@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/staging/zram/zram_drv.c b/drivers/staging/zram/zram_drv.c
index 3c8ecab..7d11c59 100644
--- a/drivers/staging/zram/zram_drv.c
+++ b/drivers/staging/zram/zram_drv.c
@@ -15,6 +15,10 @@
 #define KMSG_COMPONENT "zram"
 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
 
+#ifdef CONFIG_ZRAM_DEBUG
+#define DEBUG
+#endif
+
 #include <linux/module.h>
 #include <linux/kernel.h>
 #include <linux/bio.h>