mmc: sdhci: Add Support for ADMA2

The Standard Host Controller Interface (SDHCI) specification version
3.00 adds support for Advanced DMA (ADMA) for both 64 and 32 bit widths
of DMA. ADMA2 uses a table of descriptors for aggregating DMA requests.
This significantly improves read and write throughput.

Add Support for the same.

Signed-off-by: Faiz Abbas <faiz_abbas@ti.com>