igt: Remove duplicated macros

Introducing intel_gpu_commands.h requires removing all conflicting
macros definitions with altering the code (mostly command length).

For all commands used in IGT but not in the kernel (yet) add
intel_gpu_commands_staging.h which will keep all commands used
here only. Next import of command macros might finish verbatim
copy + removing from staging in one commit to compile cleanly.

Signed-off-by: Zbigniew Kempczyński <zbigniew.kempczynski@intel.com>
Cc: Petri Latvala <adrinael@adrinael.net>
Cc: Kamil Konieczny <kamil.konieczny@linux.intel.com>
Reviewed-by: Kamil Konieczny <kamil.konieczny@linux.intel.com>