Minor improvements to DarkSword

[st0rmsetter]

1. Removed the setTargetKaddr function, a near-identical clone of the actual set_target_kaddr function that wasn't called anywhere in the code
2. Fixed crucial error handling oversight that checked the surface variable instead of checking the success of mach_make_memory_entry_64 function like it is supposed to
3. Removed unused xpc/xpc.h import

These changes should generally make the code better