ARM: dts: am437x-idk: Add Industrial input support

The SN65HVS882 is available on the AM437x IDK and is attached to SPI1.
Input is attached to the I/O header.

Signed-off-by: Andrew F. Davis <afd@ti.com>
Reviewed-by: Roger Quadros <rogerq@ti.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>