drivers/rtc/rtc-tps65910.c: fix potential NULL-pointer dereference

The interrupt handler gets the driver data associated with the RTC
device and doesn't check it for validity.  This can cause a NULL pointer
being dereferenced when and interrupt fires before the driver data was
properly set up.

Fix this by setting the driver data earlier (before the interrupt is
requested).

Signed-off-by: Thierry Reding <treding@nvidia.com>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>