user: Fix -d debug logging for usermode emulation

Signed-off-by: Edgar E. Iglesias <edgar.iglesias@gmail.com>
diff --git a/bsd-user/main.c b/bsd-user/main.c
index 5f790b2..6018a41 100644
--- a/bsd-user/main.c
+++ b/bsd-user/main.c
@@ -866,7 +866,7 @@
         int mask;
         const CPULogItem *item;
 
-        mask = cpu_str_to_log_mask(r);
+        mask = cpu_str_to_log_mask(log_mask);
         if (!mask) {
             printf("Log items (comma separated):\n");
             for (item = cpu_log_items; item->mask != 0; item++) {