sdhci: support for ADMA only hosts

Add support for ADMA on SDHCI hosts, not supporting SDMA.

According to the SDHCI specifications a host can support ADMA but not SDMA

Signed-off-by: Richard Röjfors <richard.rojfors@mocean-labs.com>
Cc: <linux-mmc@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>