That cable is most likely a DisplayPort-to-HDMI cable not a HDMI-to-DisplayPort cable (mind the direction). While there are DP ports able to support HMDI signals (DisplayPort Dual-mode) HDMI does not support DP directly. Since HDMI data transmission is very different from DP there will be no simple (passive) cable that just re-routes some signal lines on the different connectors.
The DisplayPort signal is not compatible with DVI or HDMI. However,
Dual-mode DisplayPorts are designed to transmit a single-link DVI or
HDMI 1.2/1.4 protocol across the interface through the use of an
external passive adapter that selects the desired signal and converts
the electrical signaling from LVDS to TMDS.
DisplayPort ports can be made so that they are compatible with
single-link DVI and HDMI 1.4. Compatibility is achieved with
DisplayPort Dual-mode ports, which are marked with the ++DP logo,
using attached passive adapters.
So while these cables can connect a DP appliance to a HDMI display it's not possible to connect a HDMI appliance (such as the RPi) to a DP display.