mmc: Blackfin SD Host Controller Driver

Add SD host driver for Blackfin BF54x and BF51x.

[akpm@linux-foundation.org: fix layout, c99 warning]
Signed-off-by: Cliff Cai <cliffcai.sh@gmail.com>
Signed-off-by: Bryan Wu <cooloney@kernel.org>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Cc: <linux-mmc@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>