file_operations: get back C89 compatible initializer

Signed-off-by: Petro Karashchenko <petro.karashchenko@gmail.com>

drivers/efuse/efuse.c

@@ -88,6 +88,9 @@ static const struct file_operations g_efuseops =
   NULL,        /* seek */
   efuse_ioctl, /* ioctl */
   NULL         /* poll */
+#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
+  , NULL       /* unlink */
+#endif
 };
 
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