perf stat: Improve output

Increase size for event name to handle bigger names like
'L1-d$-prefetch-misses'

Changed scaled counters from percentage to a multiplicative
factor because the latter is more expressive.

Also aligned the scaling factor, otherwise sometimes it looks
like:

            384  iTLB-load-misses           (4.74x scaled)
         452029  branch-loads               (8.00x scaled)
           5892  branch-load-misses         (20.39x scaled)
         972315  iTLB-loads                 (3.24x scaled)

Before:
         150708  L1-d$-stores          (scaled from 23.57%)
         428804  L1-d$-prefetches      (scaled from 23.47%)
         314446  L1-d$-prefetch-misses  (scaled from 23.42%)
      252626137  L1-i$-loads           (scaled from 23.24%)
        5297550  dTLB-load-misses      (scaled from 23.96%)
      106992392  branch-loads          (scaled from 23.67%)
        5239561  branch-load-misses    (scaled from 23.43%)

After:
        1731713  L1-d$-loads               (  14.25x scaled)
          44241  L1-d$-prefetches          (   3.88x scaled)
          21076  L1-d$-prefetch-misses     (   3.40x scaled)
        5789421  L1-i$-loads               (   3.78x scaled)
          29645  dTLB-load-misses          (   2.95x scaled)
         461474  branch-loads              (   6.52x scaled)
           7493  branch-load-misses        (  26.57x scaled)

Reported-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <1246051927.2988.10.camel@hpdv5.satnam>
Signed-off-by: Ingo Molnar <mingo@elte.hu>