perf top: Fix help text alignment

Print this:

Mapped keys:
        [d]     display refresh delay.                  (2)
        [e]     display entries (lines).                (46)
        [f]     profile display filter (count).         (5)
        [F]     annotate display filter (percent).      (5%)
        [s]     annotate symbol.                        (NULL)
        [S]     stop annotation.
        [K]     hide kernel_symbols symbols.            (no)
        [U]     hide user symbols.                      (no)
        [z]     toggle sample zeroing.                  (0)
        [qQ]    quit.

instead of:

Mapped keys:
        [d]     display refresh delay.                  (2)
        [e]     display entries (lines).                (46)
        [f]     profile display filter (count).         (5)
        [F]     annotate display filter (percent).      (5%)
        [s]     annotate symbol.                        (NULL)
        [S]     stop annotation.
        [K]     hide kernel_symbols symbols.                    (no)
        [U]     hide user symbols.                      (no)
        [z]     toggle sample zeroing.                  (0)
        [qQ]    quit.
Signed-off-by: Kirill Smelkov <kirr@landau.phys.spbu.ru>
Acked-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <20100212162059.GA30041@landau.phys.spbu.ru>
Signed-off-by: Ingo Molnar <mingo@elte.hu>