target/arm: Pass security space rather than flag for AT instructions

target/arm: Pass security space rather than flag for AT instructions

At the moment we only handle Secure and Nonsecure security spaces for
the AT instructions. Add support for Realm and Root.

For AArch64, arm_security_space() gives the desired space. ARM DDI0487J
says (R_NYXTL):

  If EL3 is implemented, then when an address translation instruction
  that applies to an Exception level lower than EL3 is executed, the
  Effective value of SCR_EL3.{NSE, NS} determines the target Security
  state that the instruction applies to.

For AArch32, some instructions can access NonSecure space from Secure,
so we still need to pass the state explicitly to do_ats_write().

Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: 20230809123706.1842548-5-jean-philippe@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>