greybus: loopback: initialized ms_wait negate warning

ms_wait = 0; caught by a compiler warning.
Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>

drivers/staging/greybus/loopback.c

@@ -649,7 +649,7 @@ static void gb_loopback_calculate_stats(struct gb_loopback *gb)
 static int gb_loopback_fn(void *data)
 {
 	int error = 0;
-	int ms_wait;
+	int ms_wait = 0;
 	int type;
 	u32 size;
 	u32 low_count;