target/arm: Don't honour PSTATE.PAN when HCR_EL2.{NV, NV1} == {1, 1}

target/arm: Don't honour PSTATE.PAN when HCR_EL2.{NV, NV1} == {1, 1}

For FEAT_NV, when HCR_EL2.{NV,NV1} is {1,1} PAN is always disabled
even when the PSTATE.PAN bit is set. Implement this by having
arm_pan_enabled() return false in this situation.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Tested-by: Miguel Luis <miguel.luis@oracle.com>