Hi,
You should not need to rename the file to "ezkitutilities.c". In fact, I would probably discourage you from doing so, unless you plan on augmenting this with overloaded functions that would require C++ support.
Instead, refer to the Compiler and Libraries Manual for the section on mixing C/C++ and ASM. When calling a C function from a C++ file, simply provide a prototype to your C++ code that declares it as extern "C", such as:
extern "C" void ezInitLED(u32 LED);
Then you just call this function in your C++ code as you would any other function. The Compiler has been told that the ezInitLED function is a C function, so generates the appropriate label for the call.
Let me know if you need any more information.
Regards,
Craig.