ControllerEmu: Remove support for the "Square Stick" option

It was only used for really old joypads which we really don't want to
support. If users have these joypads, they should look into using
something at the OS level, as games shouldn't need to have this
transformation; it should be done by the OS and driver.

Source/Core/InputCommon/ControllerEmu.cpp

@@ -140,8 +140,6 @@ ControllerEmu::AnalogStick::AnalogStick(const char* const _name) : ControlGroup(
 
 	settings.emplace_back(new Setting(_trans("Radius"), 0.7f, 0, 100));
 	settings.emplace_back(new Setting(_trans("Dead Zone"), 0, 0, 50));
-	settings.emplace_back(new Setting(_trans("Square Stick"), 0));
-
 }
 
 ControllerEmu::Buttons::Buttons(const std::string& _name) : ControlGroup(_name, GROUP_TYPE_BUTTONS)