mmc: sdhci: Add ADMA2 64-bit addressing support for V4 mode

ADMA2 64-bit addressing support is divided into V3 mode and V4 mode.
So there are two kinds of descriptors for ADMA2 64-bit addressing
i.e. 96-bit Descriptor for V3 mode, and 128-bit Descriptor for V4
mode. 128-bit Descriptor is aligned to 8-byte.

For V4 mode, ADMA2 64-bit addressing is enabled via Host Control 2
register.

Signed-off-by: Chunyan Zhang <zhang.chunyan@linaro.org>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
[Ulf: Fixed conflict while applying]
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>