Cyclone V FPGA SocKit - trying to use LCD from FPGA
The SoCKit board uses a Cyclone V FPGA with an embedded Hard Processor System (HPS).

Altera's Introduction to Cyclone V Hard Processor System states:


  The HPS and FPGA portions of the device each have their own pins. Pins
  are not freely shared between the HPS and the FPGA fabric


The SoCKit board connects with the LCD via an I2C interface which uses pins C23 &amp; D22.  Those pins are part of the HPS design and so they are not directly accessible to the FPGA fabric.

To determine if a given pin is accessible by the FPGA, or by the HPS you will need to check the pinout for your FPGA.  In the case of the SoCKit design, the FPGA is in a FCSXFC6 package.