Cleanup: spelling

Includes fixes to misspelled function names.

Ref D11280

source/blender/gpu/shaders/material/gpu_shader_material_tex_noise.glsl

@@ -2,7 +2,7 @@
  * coordinates to act as a seed since the noise functions don't have seed values.
  * A seed value is needed for generating distortion textures and color outputs.
  * The offset's components are in the range [100, 200], not too high to cause
- * bad precision and not to small to be noticeable. We use float seed because
+ * bad precision and not too small to be noticeable. We use float seed because
  * OSL only support float hashes.
  */