IOS: Remove unnecessary and unused PrepareForState

[leoetlino]

PrepareForState is now unnecessary with the new implementation of
HostFileSystem::DoState, which does what the old implementation
(CWII_IPC_HLE_Device_FileIO::PrepareForState) used to do.

master:

dolphin/Source/Core/Core/IOS/FS/HostBackend/FS.cpp

Lines 238 to 242 in 2f85b80

	void HostFileSystem::DoState(PointerWrap& p)
	{
	// Temporarily close the file, to prevent any issues with the savestating of /tmp
	for (Handle& handle : m_handles)
	handle.host_file.reset();

2015 Dolphin:

dolphin/Source/Core/Core/IPC_HLE/WII_IPC_HLE_Device_FileIO.cpp

Lines 360 to 365 in 7d80aae

	void CWII_IPC_HLE_Device_FileIO::PrepareForState(PointerWrap::Mode mode)
	{
	// Temporally close the file, to prevent any issues with the savestating of /tmp
	// it can be opened again with another call to OpenFile()
	m_file.reset();
	}