dev-arm: Introduce the active boolean for ArmInterruptPin

dev-arm: Introduce the active boolean for ArmInterruptPin

The active boolean will specify if the interrupt line is active
or not (high if it is active high or low if it is active low).

This is decoupled from the interrupt being in a pending state
within the GIC, and it can be used by a peripheral to query the
status of its interrupt pin

Change-Id: I18445b891a75767c8a72e9a7044d6d75fdb7e224
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/31934
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>