This patch reverts the commit dba3c29e.

After bisecting, this commit dba3c29e is found to ruin micro-SD card data
(writing incorrect file, or fs is corrupt after several times mount)
on the beagle-xm revB, and reverting the commit will fix the problem.

Also from TRM of OMAP3/OMAP4/DM37x, the below is mentioned about
the Auto CMD12 Enable bit.
        - SDIO does not support this feature.
        - SD card only.
Looks it is not suitable to always enable Auto CMD12 in host controller
driver.

Considered that the commit is not mature enough, so ask to revert it
first.

Cc: Balaji T K <balajitk@ti.com>
Cc: Venkatraman S <svenkatr@ti.com>
Buglink: https://lkml.org/lkml/2012/6/10/225Reported-by: Paolo Pisati <p.pisati@gmail.com>
Reported-bisected-and-tested-by: Ming Lei <ming.lei@canonical.com>
Signed-off-by: Ming Lei <ming.lei@canonical.com>
Acked-by: Venkatraman S <svenkatr@ti.com>
Signed-off-by: Chris Ball <cjb@laptop.org>