delayacct: track delays from IRQ/SOFTIRQ

Delay accounting does not track the delay of IRQ/SOFTIRQ.  While
IRQ/SOFTIRQ could have obvious impact on some workloads productivity, such
as when workloads are running on system which is busy handling network
IRQ/SOFTIRQ.

Get the delay of IRQ/SOFTIRQ could help users to reduce such delay.  Such
as setting interrupt affinity or task affinity, using kernel thread for
NAPI etc.  This is inspired by "sched/psi: Add PSI_IRQ to track
IRQ/SOFTIRQ pressure"[1].  Also fix some code indent problems of older
code.

And update tools/accounting/getdelays.c:
    / # ./getdelays -p 156 -di
    print delayacct stats ON
    printing IO accounting
    PID     156

    CPU             count     real total  virtual total    delay total  delay average
                       15       15836008       16218149      275700790         18.380ms
    IO              count    delay total  delay average
                        0              0          0.000ms
    SWAP            count    dela...