mmc: exynos_dw_mmc: Fix obtaining the base address of controller

mmc: exynos_dw_mmc: Fix obtaining the base address of controller

Getting the base address with outdated fdtdec_get_addr() API and further
casting it to (void *) leads to next build warning on ARM64 platforms:

    In function 'exynos_dwmci_get_config':
        warning: cast to pointer from integer of different size
        [-Wint-to-pointer-cast]
            host->ioaddr = (void *)base;

Use livetree API instead (dev_read_addr_ptr()), which handles this
correctly.

Fixes: a082a2dde061 ("EXYNOS5: DWMMC: Added FDT support for DWMMC")
Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org>
Signed-off-by: Minkyu Kang <mk7.kang@samsung.com>