ARM: tegra: irq: Add missing irq.h include

Some of the functions implemented are flagged as not having a prototype
defined when building with W=1. Include the header to avoid these build
warnings.
Signed-off-by: Thierry Reding <treding@nvidia.com>

arch/arm/mach-tegra/irq.c

@@ -29,6 +29,7 @@
 
 #include "board.h"
 #include "iomap.h"
+#include "irq.h"
 
 #define SGI_MASK 0xFFFF