x86: quark: Fix boot breakage

With driver model timer conversion, quark based board does not boot
any more as mdelay() is called during quark_pcie_early_init() which
is before driver model gets initialized. Fix this breakage.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>