asus-laptop: Do not call HWRS on init

Since commit 8871e99f ('asus-laptop: HRWS/HWRS typo'), module
initialisation is very slow on the Asus UL30A.  The HWRS method takes
about 12 seconds to run, and subsequent initialisation also seems to
be delayed.  Since we don't really need the result, don't bother
calling it on init.  Those who are curious can still get the result
through the 'infos' device attribute.

Update the comment about HWRS in show_infos().

Reported-by: ryan <draziw+deb@gmail.com>
References: http://bugs.debian.org/692436


Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Corentin Chary <corentin.chary@gmail.com>
Signed-off-by: Matthew Garrett <matthew.garrett@nebula.com>