headers: remove sched.h from interrupt.h

After m68k's task_thread_info() doesn't refer to current,
it's possible to remove sched.h from interrupt.h and not break m68k!
Many thanks to Heiko Carstens for allowing this.

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
diff --git a/arch/arm/mach-integrator/pci_v3.c b/arch/arm/mach-integrator/pci_v3.c
index 901cc20..148d25f 100644
--- a/arch/arm/mach-integrator/pci_v3.c
+++ b/arch/arm/mach-integrator/pci_v3.c
@@ -31,6 +31,7 @@
 
 #include <mach/hardware.h>
 #include <asm/irq.h>
+#include <asm/signal.h>
 #include <asm/system.h>
 #include <asm/mach/pci.h>
 #include <asm/irq_regs.h>