shader_recompiler: Remove S32 IR type

The frontend IR opcodes do not distinguish between signed and unsigned integer types.

Fixes broken shaders when IR validation/graphics debugging is enabled for shaders that used BitCastS32F32

src/shader_recompiler/frontend/ir/opcodes.h

@@ -38,7 +38,6 @@ constexpr Type U8{Type::U8};
 constexpr Type U16{Type::U16};
 constexpr Type U32{Type::U32};
 constexpr Type U64{Type::U64};
-constexpr Type S32{Type::S32};
 constexpr Type F16{Type::F16};
 constexpr Type F32{Type::F32};
 constexpr Type F64{Type::F64};