sdhci: add adma descriptor set call

The code to write the ADMA descriptor into memory is repeated several
times throughout sdhci_adma_table_pre, and thus should be moved into a
common function.  This will also be useful if the patch to make the write
more efficient is accepted.

Signed-off-by: Ben Dooks <ben-linux@fluff.org>
Cc: Pierre Ossman <pierre@ossman.eu>
Cc: <linux-mmc@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>