imx: Add support for PLEP_TEMPERATURE and PLEP_TEMP_MODE to get/set_opt

These are used for setting the temperature for use in temperature-based
waveform selection.

Signed-off-by: Andrew Cox <andrew.cox@plasticlogic.com>
epson: only use the new sysfs path

Now that the modelffb driver is always a platform driver, always
use the same sysfs path and not the SPI bus paths any more.

Signed-off-by: Guillaume Tucker <guillaume.tucker@plasticlogic.com>
imx: use new PLEP_TEMPERATURE_AUTO hardware option id
epson: add missing call to open control interface

Put back the line to open the control interface using fopen.
Somehow this got broken when the SPI sysfs interface was removed.
ChangeLog v012 -> v013