Input: synaptics-rmi4 - fix maximum size check for F12 control register 8

Input: synaptics-rmi4 - fix maximum size check for F12 control register 8

commit e4add7b6beaff4061693d0632bc1dcb306edba10 upstream.

According to the RMI4 spec the maximum size of F12 control register 8 is
15 bytes. The current code incorrectly reports an error if control 8 is
greater then 14. Making sensors with a control register 8 with 15 bytes
unusable.

Signed-off-by: Andrew Duggan <aduggan@synaptics.com>
Reported-by: Chris Healy <cphealy@gmail.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>