video_core/GPU Implemented the GPU PFIFO puller semaphore operations. (#1908)

* Implemented the puller semaphore operations.

* Nit: Fix 2 style issues

* Nit: Add Break to default case.

* Fix style.

* Update for comments. Added ReferenceCount method

* Forgot to remove GpuSmaphoreAddress union.

* Fix the clang-format issues.

* More clang formatting.

* two more white spaces for the Clang formatting.

* Move puller members into the regs union

* Updated to use Memory::WriteBlock instead of Memory::Write*

* Fix clang style issues

* White space clang error

* Removing unused funcitons and other pr comment

* Removing unused funcitons and other pr comment

* More union magic for setting regs value.

* union magic refcnt as well

*  Remove local var

* Set up the regs and regs_assert_positions up properly

* Fix clang error