FS: Don't build block driver proxy if PSEUDOFS_OPERATIONS are disabled.

fs/vfs/fs_open.c

@@ -140,7 +140,8 @@ int open(const char *path, int oflags, ...)
   inode = desc.node;
   DEBUGASSERT(inode != NULL);
 
-#if !defined(CONFIG_DISABLE_MOUNTPOINT)
+#if !defined(CONFIG_DISABLE_MOUNTPOINT) && \
+    !defined(CONFIG_DISABLE_PSEUDOFS_OPERATIONS)
    /* If the inode is block driver, then we may return a character driver
     * proxy for the block driver.  block_proxy() will instantiate a BCH
     * character driver wrapper around the block driver, open(), then