hikey: remove delay after eMMC initialized

commit 386b14bf64124ebf0368eab33ef07603e0c3138a
Author: Haojian Zhuang <haojian.zhuang@linaro.org>
Date:   Wed Nov 21 09:19:49 2018 +0800

    mmc: poll eMMC status after EXT_CSD command

    EXT_CSD command needs to access data from eMMC device. Add the
    operation of polling eMMC device status. Make sure the command is
    finished.
Signed-off-by: Haojian Zhuang <haojian.zhuang@linaro.org>

A hacked delay time can't fit each eMMC device. Since the above commit
enables the polling operation, remove the hacked delay time now.
Signed-off-by: Haojian Zhuang <haojian.zhuang@linaro.org>

plat/hisilicon/hikey/hikey_bl2_setup.c

@@ -336,7 +336,6 @@ void bl2_platform_setup(void)
 	params.flags = MMC_FLAG_CMD23;
 	info.mmc_dev_type = MMC_IS_EMMC;
 	dw_mmc_init(&params, &info);
-	mdelay(20);
 
 	hikey_io_setup();
 }