target-arm: add CPREG secure state support

target-arm: add CPREG secure state support

Prepare ARMCPRegInfo to support specifying two fieldoffsets per
register definition. This will allow us to keep one register
definition for banked registers (different offsets for secure/
non-secure world).

Also added secure state tracking field and flags.  This allows for
identification of the register info secure state.

Signed-off-by: Fabian Aggeler <[email protected]>
Signed-off-by: Greg Bellows <[email protected]>
Reviewed-by: Peter Maydell <[email protected]>
Message-id: 1416242878[email protected]
Signed-off-by: Peter Maydell <[email protected]>