[Build] Remove deprecated submodule

Author: YWHyuk

.gitmodules

@@ -7,9 +7,6 @@
 [submodule "PyTorchSimBackend/extern/booksim"]
 	path = PyTorchSimBackend/extern/booksim
 	url = https://github.com/PSAL-POSTECH/booksim.git
-[submodule "PyTorchSimBackend/extern/torch2timeloop"]
-        path = PyTorchSimBackend/extern/torch2timeloop
-        url = https://github.com/Accelergy-Project/pytorch2timeloop-converter.git
 [submodule "PyTorchSimBackend/extern/ramulator2"]
 	path = PyTorchSimBackend/extern/ramulator2
 	url = https://github.com/PSAL-POSTECH/ramulator2