mmc: rockchip_sdhci: Fix use of device private data

mmc: rockchip_sdhci: Fix use of device private data

The device private data is misused in rockchip_sdhci_of_to_plat and
rockchip_sdhci_execute_tuning.

In these functions dev_get_priv is assigned to struct sdhci_host:

  struct sdhci_host *host = dev_get_priv(dev);

Instead, the sdhci host should refer to host in struct rockchip_sdhc:

  struct rockchip_sdhc *priv = dev_get_priv(dev);
  struct sdhci_host *host = &priv->host;

Because host is the first member in struct rockchip_sdhc this is not a
real problem, lets fix it anyway and also use priv name consistently.

Signed-off-by: Jonas Karlman <jonas@kwiboo.se>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>