Fix: SyntaxWarning invalid escape sequence

In every regex the escape sequence is broken and running the script
results in many warnings like:

$noise_parse.py:460: SyntaxWarning: invalid escape sequence '\s'
  s = re.search("softirq_entry:\s+vec=[0-9] \[action=(.+?)\]", line, re.S)

Fixed the warning adding another backslash (\).

Signed-off-by: Marco Crivellari <marco.crivellari@suse.com>