ARM: tegra: irq: add wake up handling

Add the wake up handling for legacy irq controller, and using
IRQCHIP_MASK_ON_SUSPEND for wake irq handling.

Based on the work by:
Varun Wadekar <vwadekar@nvidia.com>

Signed-off-by: Joseph Lo <josephl@nvidia.com>
Signed-off-by: Stephen Warren <swarren@nvidia.com>

arch/arm/mach-tegra/irq.h

@@ -19,4 +19,10 @@
 
 bool tegra_pending_sgi(void);
 
+#ifdef CONFIG_PM_SLEEP
+int tegra_legacy_irq_syscore_init(void);
+#else
+static inline int tegra_legacy_irq_syscore_init(void) { return 0; }
+#endif
+
 #endif