kprobes: use do_IRQ() in lkdtm

Current lkdtm code puts a probe on __do_IRQ for some of the kdump test
cases.  Since __do_IRQ is deprecated, change lkdtm code to use do_IRQ
function.

Signed-off-by: M. Mohan Kumar <mohan@in.ibm.com>
Cc: Ankita Garg <ankita@in.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Masami Hiramatsu <mhiramat@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>