dts: add sdhci,auto-cmd12 field for p4080 device tree

Signed-off-by: Roy Zang <tie-fei.zang@freescale.com>
Cc: Jerry Huang <Chang-Ming.Huang@freescale.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Kumar Gala <galak@gate.crashing.org>
Cc: Grant Likely <grant.likely@secretlab.ca>
Cc: <linux-mmc@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>