target/arm: Implement MDCR_EL2.TDCC and MDCR_EL3.TDCC traps

target/arm: Implement MDCR_EL2.TDCC and MDCR_EL3.TDCC traps

FEAT_FGT also implements an extra trap bit in the MDCR_EL2 and
MDCR_EL3 registers: bit TDCC enables trapping of use of the Debug
Comms Channel registers OSDTRRX_EL1, OSDTRTX_EL1, MDCCSR_EL0,
MDCCINT_EL0, DBGDTR_EL0, DBGDTRRX_EL0 and DBGDTRTX_EL0 (and their
AArch32 equivalents).  This trapping is independent of whether
fine-grained traps are enabled or not.

Implement these extra traps.  (We don't implement DBGDTR_EL0,
DBGDTRRX_EL0 and DBGDTRTX_EL0.)

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Tested-by: Fuad Tabba <tabba@google.com>
Message-id: 20230130182459.3309057-23-peter.maydell@linaro.org
Message-id: 20230127175507.2895013-23-peter.maydell@linaro.org