Remove unused code

[radarhere]

When decoding JPEG2000 images in C, we allow for 3 codecs.

Pillow/src/decode.c

Lines 871 to 876 in 7dbcb32

	if (strcmp(format, "j2k") == 0) {
	codec_format = OPJ_CODEC_J2K;
	} else if (strcmp(format, "jpt") == 0) {
	codec_format = OPJ_CODEC_JPT;
	} else if (strcmp(format, "jp2") == 0) {
	codec_format = OPJ_CODEC_JP2;

But only 2 are ever set in Python.

Pillow/src/PIL/Jpeg2KImagePlugin.py

Lines 253 to 260 in 7dbcb32

	self.codec = "j2k"
	self._size, self._mode = _parse_codestream(self.fp)
	self._parse_comment()
	else:
	sig = sig + self.fp.read(8)
	if sig == b"\x00\x00\x00\x0cjP \x0d\x0a\x87\x0a":
	self.codec = "jp2"