perf tools: Align long options which have no short forms

Before:

$ ./perf kmem
...
    -l, --line <num>      show n lines
    --raw-ip              show raw ip instead of symbol

After:

$ ./perf kmem
...
    -l, --line <num>      show n lines
        --raw-ip          show raw ip instead of symbol

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
LKML-Reference: <4B20A1A9.3040104@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>