Input: ti_am335x_tsc - lower the X and Y sampling time

The open delay time has to be applied only on the first sample of the
X/Y coordinates because on the following samples the ADC channel is not
changed. Removing this time from the samples after the first one,
"ti,coordinate-readouts" greater than 1, decreases the total acquisition
time, allowing to increase the number of acquired coordinates in the time
unit.

Signed-off-by: Dario Binacchi <dariobin@libero.it>
Link: https://lore.kernel.org/r/20211212125358.14416-4-dariobin@libero.it


Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>