[ARM] 4690/1: PXA: fix CKEN corruption in PXA27x AC97 cold reset code

Fix CKEN register corruption in the PXA27x cold reset code
located in sound/arm/pxa27x-ac97.c. The problem has been
introduced with a pxa_set_cken() function change in linux 2.6.23.
This patch is based on patch 4527/1 that fixes the same problem in
the ASoC PXA-AC97 driver. Additionally a definition for the CKEN
index value is added and applied to both PXA AC97 drivers.

Signed-off-by: Michael Brunner <mibru@gmx.de>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>