mmc: sdhci: Parameterize ADMA sizes and alignment

In preparation for 64-bit ADMA, parameterize ADMA sizes
and alignment.  64-bit ADMA has a larger descriptor
because it contains a 64-bit address instead of a 32-bit
address.  Also data must be 8-byte aligned instead
of 4-byte aligned.  Consequently, sdhci_host members
are added for descriptor, table, and buffer sizes
and alignment.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>