Simplify code now that I;16* modes are the only IMAGING_TYPE_SPECIAL

[radarhere]

#9053 removed BGR;15, BGR;16 and BGR;24, so

Pillow/src/libImaging/Storage.c

Lines 133 to 141 in 5122c83

	} else if (isModeI16(mode)) {
	/* EXPERIMENTAL */
	/* 16-bit raw integer images */
	im->bands = 1;
	im->pixelsize = 2;
	im->linesize = xsize * 2;
	im->type = IMAGING_TYPE_SPECIAL;
	strcpy(im->arrow_band_format, "s");
	strcpy(im->band_names[0], "I");

is the only IMAGING_TYPE_SPECIAL left.