Clean up MTLSurfaceDataBase.h

MTLSurfaceDataBase.h file contains BMTLSDOps struct. Some cleanup is needed in this file.
This was brought up during code review - https://github.com/openjdk/jdk/pull/2403#discussion_r592840260

1) Verify that all fields in this structure are needed. If unused, remove them. Note that a clean build will be needed for testing if this structure is modified.

2) The comments describing this structure has some invalid reference to WindowsXP etc. Review and clean up the description as well.