The current implementation of the delay_us, delay_ms and pin_write functions are specific to the Nordic nRF5 SDK. You'll have to modify these functions and the includes to fit your micro and environment.
Define your register select, enable, data 4, data 5, data 6, and data 7 pins in main. Call lcd_init().
This uses a custom data bus implemented in lcd_write_data(), as long as the gpio pins are defined correctly in main, and provided to the lcd_init() function, you should have no problem communicating with the display. Functions for printing to the display are defined in the lcd_16x2.h file.