lis3: fix show rate for 8 bits chips

Originally the driver was only targeted to 12bits sensors.  When support
for 8bits sensors was added, some slight difference in the registers were
overlooked.  This should fix it, both for initialization, and for
displaying the rate.

Reported-by: Kalhan Trisal <kalhan.trisal@intel.com>
Reported-by: Christoph Plattner <christoph.plattner@gmx.at>
Tested-by: Christoph Plattner <christoph.plattner@gmx.at>
Tested-by: Samu Onkalo <samu.p.onkalo@nokia.com>
Signed-off-by: Éric Piel <eric.piel@tremplin-utc.net>
Signed-off-by: Samu Onkalo <samu.p.onkalo@nokia.com>
Cc: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>