mmc: exynos_dw_mmc: Extend dm_dwmci_ops without code duplication

mmc: exynos_dw_mmc: Extend dm_dwmci_ops without code duplication

Instead of extending dm_dwmci_ops by copy-pasting the structure code
first, copy the actual structure data with memcpy() and then set the
.execute_tuning field. Now if struct dm_dwmci_ops gets modified in
future, these changes will be automatically reflected in struct
exynos_dwmmc_ops, which prevents possible issues in future. It also
avoids code duplication.

No functional change, but it can prevent possible isssues in future.

Fixes: eda4bd29929c ("mmc: exynos_dw_mmc: add support for MMC HS200 and HS400 modes")
Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org>
Reviewed-by: Anand Moon <linux.amoon@gmail.com>
Signed-off-by: Peng Fan <peng.fan@nxp.com>