[ARM] integrator: fix pci_v3 compile error with DEBUG_LL

If DEBUG_LL is enabled, we want to use get_irq_regs(), but this
causes a build error due to the inline function missing.  Add
the necessary header file.
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

arch/arm/mach-integrator/pci_v3.c

@@ -33,6 +33,7 @@
 #include <asm/irq.h>
 #include <asm/system.h>
 #include <asm/mach/pci.h>
+#include <asm/irq_regs.h>
 
 #include <asm/hardware/pci_v3.h>