gpu: nvgpu: unit: add tests for gk20a fifo HAL

Add unit tests for the following HALs:
- gk20a_fifo_init_pbdma_map
- gk20a_fifo_get_runlist_timeslice
- gk20a_fifo_get_pb_timeslice
- gk20a_fifo_intr_1_enable
- gk20a_fifo_intr_1_isr
- gk20a_fifo_intr_handle_chsw_error
- gk20a_fifo_intr_handle_runlist_event
- gk20a_fifo_pbdma_isr

Jira NVGPU-4386

Change-Id: Iab518e3bc3f8fabdfb32172db8de300dd4142a53
Signed-off-by: Thomas Fleury <tfleury@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/2256264
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>

userspace/SWUTS.h

@@ -46,6 +46,7 @@
  *   - @ref SWUTS-fifo-engine-gp10b
  *   - @ref SWUTS-fifo-engine-gv100
  *   - @ref SWUTS-fifo-engine-gv11b
+ *   - @ref SWUTS-fifo-fifo-gk20a
  *   - @ref SWUTS-fifo-pbdma
  *   - @ref SWUTS-fifo-pbdma-gm20b
  *   - @ref SWUTS-fifo-pbdma-gp10b