[ARM] pxa/em-x270: always register AC97 controller device

After commit 6b849bcf (ASoC: Convert PXA
AC97 driver to probe with the platform device) AC97 controller device
should be registered explicitly for both ASoC and generic AC97 drivers

Signed-off-by: Mike Rapoport <mike@compulab.co.il>
Signed-off-by: Eric Miao <eric.y.miao@gmail.com>