Remove heading spaces in softirq names displayed by mpstat for easier reading.

Remove heading spaces in softirq names displayed by mpstat for easier reading.

Output from mpstat -I SCPU was sometimes difficult to read because
of softirq names which are sometimes too long. So remove heading spaces
for easier reading.
Before:
09:46:05 PM  CPU           HI/s        TIMER/s       NET_TX/s       NET_RX/s        BLOCK/s BLOCK_IOPOLL/s      TASKLET/s        SCHED/s      HRTIMER/s          RCU/s
09:46:05 PM    0       0.00     783.63       0.17       9.09       4.52       0.00       3.25     154.86       0.02      66.59
After:
09:57:02 PM  CPU       HI/s    TIMER/s   NET_TX/s   NET_RX/s    BLOCK/s BLOCK_IOPOLL/s  TASKLET/s    SCHED/s  HRTIMER/s      RCU/s
09:57:02 PM    0       0.00     752.30       0.17       7.79       3.80       0.00       2.86     168.52       0.01      64.77