updated clamped vector load code to use IR node make methods
updated clamped vector load code to use IR node make methods


Former-commit-id: b54feb2ba537378820ee08f8a19e910e64e43e96
Trass3r/Halide,darkbuck/Halide,Trass3r/Halide,darkbuck/Halide,darkbuck/Halide,darkbuck/Halide,darkbuck/Halide,Trass3r/Halide,darkbuck/Halide,Trass3r/Halide,Trass3r/Halide,Trass3r/Halide,darkbuck/Halide,Trass3r/Halide