Remove unused HSV and LAB matrix conversion from C

[radarhere]

The only place that Python attempts to convert a matrix is

Pillow/src/PIL/Image.py

Lines 1079 to 1082 in 6a8de89

	if mode not in ("L", "RGB"):
	msg = "illegal conversion"
	raise ValueError(msg)
	im = self.im.convert_matrix(mode, matrix)

So HSV and LAB images will never be sent to the C layer.