[ARM] pxa/cm-x300: add revision difference handling

Different revisions of CM-X300 use different pins for several functions.
Make the kernel aware of it.

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