mmc: sdhci: enable 64-bit DMA support only if chipset supports 64-bit

This patch adds check to enable the 64-bit DMA only if the chipset
supports the same.

Change-Id: I5dbe6f91d5e530b289f4cf395ae7b673acd85fcf
Signed-off-by: Subhash Jadavani <subhashj@codeaurora.org>
[xiaonian@codeaurora.org: fixed trivial merge conflicts]
Signed-off-by: Xiaonian Wang <xiaonian@codeaurora.org>