DT: mxs-lradc: fix ranges of ts properties

This patch fixes off-by-one issues in the devicetree binding of
mxs-lradc.

According to the i.MX23 and i.MX28 reference manuals [1][2] the range of
NUM_SAMPLES is 0..31, but property ave-ctrl is substracted by 1 before used.

Considering all limitations the range of DELAY is 1..2047, but also
property ave-delay is substracted by 1 before used.

The patch has been suggested by Hartmut Knaack and Kristina Martsenko.

[1] - http://cache.freescale.com/files/dsp/doc/ref_manual/IMX23RM.pdf
[2] - http://cache.freescale.com/files/dsp/doc/ref_manual/MCIMX28RM.pdf



Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>