dev-arm: Create a getter for ArmInterruptPin ID number

A pin owner might want to know which is the irq number
associated with the pin.

Change-Id: I095393d4d25efe13eb2a75a0b0b055d386c2c126
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Ciro Santilli <ciro.santilli@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/12298
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

src/dev/arm/base_gic.hh

@@ -128,6 +128,9 @@ class ArmInterruptPin : public SimObject
      */
     void setThreadContext(ThreadContext *tc);
 
+    /** Get interrupt number */
+    uint32_t num() const { return intNum; }
+
     /** Signal an interrupt */
     virtual void raise() = 0;
     /** Clear a signalled interrupt */