irqtop: add per-cpu stats

irqtop: add per-cpu stats

irqtop | total: 1245107402 delta: 7394 | ws.net.home | 2021-02-24 20:11:09+01:00

        cpu0 cpu1 cpu2 cpu3 cpu4 cpu5 cpu6 cpu7
  %irq: 12.9 13.0 12.8 11.9 12.4 13.4 11.6 12.0
%delta: 13.7  9.7 22.6  7.9  9.5 17.5  8.3 10.8

       IRQ      TOTAL      DELTA NAME
       LOC  989162414       6111 Local timer interrupts
       TLB  100492740         67 TLB shootdowns
       CAL   95058001        321 Function call interrupts
        42   23893801        241 IR-PCI-MSI 1048576-edge nvidia
        30   20209392        494 IR-PCI-MSI 327680-edge xhci_hcd
       RES   12996335         86 Rescheduling interrupts
        29    1354219          4 IR-PCI-MSI 512000-edge ahci[0000:00:1f.2]
        41     682653         31 IR-PCI-MSI 409600-edge eno1
   ...

Signed-off-by: Karel Zak <kzak@redhat.com>