i.MX: Split the CCM class into an abstract base class and a concrete class

i.MX: Split the CCM class into an abstract base class and a concrete class

The IMX_CCM class is now the base abstract class that is used by EPIT
and GPT timer implementation.

IMX31_CCM class is the concrete class implementing CCM for i.MX31 SOC.

For now the i.MX25 continues to use the i.MX31 CCM implementation.

An i.MX25 specific CCM will be introduced in a later patch.

We also rework initialization to stop using deprecated sysbus device init.

Signed-off-by: Jean-Christophe Dubois <[email protected]>
Reviewed-by: Peter Crosthwaite <[email protected]>
Message-id: fd3c7f87b50f5ebc99ec91f01413db35017f116d.1449528242[email protected]
Signed-off-by: Peter Maydell <[email protected]>