Don't pass uniform arrays in GrGLNonlinearColorSpaceXformEffect

Don't pass uniform arrays in GrGLNonlinearColorSpaceXformEffect

This avoids a problem where passing a uniform array as a function
array sometimes gets lost.

Instead of passing the uniform array as an argument to the
transfer function evaluation function, create two separate
transfer function evaluation functions that read the uniforms
directly.

BUG=723133

Change-Id: Ib46b99efdbc04ce0201644ebbc1dfd4cb27e9276
Reviewed-on: https://skia-review.googlesource.com/17293
Commit-Queue: Brian Osman <brianosman@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>