Input: kxtj9 - who_am_i check value and initial data rate fixes

Several fixes based on customer feedback:

* WHO_AM_I value has changed since preliminary parts used for initial
  testing;

* Output of le16_to_cpu must be saved to memory before shifting to
  preserve sign;

* Initial data rate was not extracted from data control register init.
  This was causing the initial data rate to be set to maximum until
  it was changed. To fix this problem, it made more sense to specify
  initial data rate and extract the register mask from that.

Signed-off-by: Chris Hudson <chudson@kionix.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>