x86: smarten /proc/interrupts output for new counters

Now /proc/interrupts of tip tree has new counters:

  PLT: Platform interrupts

Format change of output, as like that by commit:

  commit 7a81d9a7
  x86: smarten /proc/interrupts output

should be applied to these new counters too.

Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Cc: Jan Beulich <jbeulich@novell.com>
LKML-Reference: <49C98DEA.8060208@jp.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>