eeepc-laptop: move platform device initialisation to a separate function

This moves the sysfs_create_group() call just after the declaration of
the platform device attributes.  It should make it easier to examine
the implementation of the platform device attributes in isolation
from the rest of the code.  (The next commit will apply this pattern
to all of the sub-devices as well).

Signed-off-by: Alan Jenkins <alan-jenkins@tuffmail.co.uk>
Signed-off-by: Len Brown <len.brown@intel.com>