lis3: add skeletons for interrupt handlers

Original lis3 driver didn't provide interrupt handler(s) for click or
threshold event handling.  This patch adds threaded handlers for one or
two interrupt lines for 8 bit device.  Actual content for interrupt
handling is provided in the separate patch.

Signed-off-by: Samu Onkalo <samu.p.onkalo@nokia.com>
Tested-by: Daniel Mack <daniel@caiaq.de>
Acked-by: Eric Piel <eric.piel@tremplin-utc.net>
Cc: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>