The register mapping for the IIO driver for the Liteon Light and Proximity
sensor LTR501 interrupt mode is interchanged (ALS/PS).
There is a register called INTERRUPT register (address 0x8F)
Bit 0 represents PS measurement trigger.
Bit 1 represents ALS measurement trigger.
This two bit fields are interchanged within the driver.
see datasheet page 24:
http://optoelectronics.liteon.com/upload/download/DS86-2012-0006/S_110_LTR-501ALS-01_PrelimDS_ver1%5B1%5D.pdf