nvme: Just return 0 by get-reg and set-reg commands if not error

The err variable is set 0 if no error so just return 0 instead.

Signed-off-by: Tokunori Ikegami <[email protected]>

nvme.c

@@ -5593,7 +5593,7 @@ static int get_register(int argc, char **argv, struct command *cmd, struct plugi
 	else
 		munmap(bar, getpagesize());
 
-	return err;
+	return 0;
 }
 
 static void nvme_set_register(void *bar, int offset, uint64_t value)
@@ -5650,7 +5650,7 @@ static int set_register(int argc, char **argv, struct command *cmd, struct plugi
 
 	munmap(bar, getpagesize());
 
-	return err;
+	return 0;
 }
 
 static int get_property(int argc, char **argv, struct command *cmd, struct plugin *plugin)