Currently, the DMA addresses are casted to (u64) for the upper 32bits
to avoid "right shift count >= width of type" warning.

<linux/kernel.h> provides macros to address this, and I like the macro
names are self-documenting.

I introduced a new helper, sdhci_set_adma_addr() to avoid the code
duplication.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>