[PATCH] sysrq: include interrupt.h instead of irq.h

With "cpumask: update irq_desc to use cpumask_var_t"
we get this build failure on s390:

  CC      drivers/char/sysrq.o
In file included from drivers/char/sysrq.c:38:
include/linux/irq.h: In function 'init_alloc_desc_masks':
include/linux/irq.h:442: error: dereferencing pointer to incomplete type

drivers/char/sysrq.c should include interrupt.h instead of irq.h.

Cc: Mike Travis <travis@sgi.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>