Core: Remove unused function Callback_ISOName()

[lioncash]

No description provided.

[phire]

Can we make sure this isn't called from commented out code?

[delroth]

$ grep -r Callback_ISOName .
./Core/Core/Core.cpp:const char *Callback_ISOName(void);
./Core/Core/Core.cpp:// Callback_ISOName: Let the DSP emulator get the game name
./Core/Core/Core.cpp:const char *Callback_ISOName()