GL_DEPTH_COMPONENT24 was missing.
It seems to be in all other functions in this file.

Fixes debug assert in OGLES3ColourGrading

Change-Id: Ifb8fe8dc9248f5acbd9cac3622c3335525711bda
Reviewed-on: https://swiftshader-review.googlesource.com/14248Tested-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>