HID: roccat: cleanup of pyra module

Partially removed unneeded informations and data caching.
Moved code nearer to format of newer drivers.
Added "info" sysfs attribute to support device reset and deprecate
"firmware_version" attribute.

Signed-off-by: Stefan Achatz <erazor_de@users.sourceforge.net>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>