mmc: exynos_dw_mmc: Add support for ARM64 Exynos chips

mmc: exynos_dw_mmc: Add support for ARM64 Exynos chips

Add the compatible entry and corresponding chip data for Exynos7
compatible chips, which covers modern ARM64 based Exynos chips. They
have some differences w.r.t. old ARM32 Exynos chips:
  - CLKSEL register offset is different
  - 64-bit IDMAC descriptor and 64-bit IDMAC registers are used
    (implemented in dw_mmc core driver)

In terms of the driver implementation, the CIU clock is obtained via CCF
framework (as opposed to ad-hoc clock driver implementation for ARM32
chips).

Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org>
Signed-off-by: Minkyu Kang <mk7.kang@samsung.com>