target-arm: add banked register accessors

If EL3 is in AArch32 state certain cp registers are banked (secure and
non-secure instance). When reading or writing to coprocessor registers
the following macros can be used.

- A32_BANKED macros are used for choosing the banked register based on provided
  input security argument.  This macro is used to choose the bank during
  translation of MRC/MCR instructions that are dependent on something other
  than the current secure state.
- A32_BANKED_CURRENT macros are used for choosing the banked register based on
  current secure state.  This is NOT to be used for choosing the bank used
  during translation as it breaks monitor mode.

If EL3 is operating in AArch64 state coprocessor registers are not
banked anymore. The macros use the non-secure instance (_ns) in this
case, which is architecturally mapped to the AArch64 EL register.

Signed-off-by: Sergey Fedorov <s.fedorov@samsung.com>
Signed-off-by: Fabian Aggeler <aggelerf@ethz.ch>
Signed-off-by: Greg Bellows <greg.bellows@linaro.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: 1416242878-876-4-git-send-email-greg.bellows@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
