gpu: nvgpu: unit: add tests for TSG hal

Add unit tests for:
- gv11b_tsg_init_eng_method_buffers
- gv11b_tsg_deinit_eng_method_buffers
- gv11b_tsg_bind_channel_eng_method_buffers
- gv11b_tsg_unbind_channel_check_eng_faulted

Note: gv11b_tsg_enable was already tested as part of TSG common.

Added SWUTS documentation for above tests.

Modified gv11b_tsg_init_eng_method_buffers to inline computation
of method buffer size, as existing static function could never
return 0, making one branch not testable.

Added dummy IO register spaces for PFB, CE, PBUS and HSUB_COMMON,
so that g->ops.mm.init_mm_support can be called as part of
test_fifo_init_support. MM support is needed to test allocation
and mapping of DMA buffers.

Jira NVGPU-3788

Change-Id: I5356531b23c0456662187d16b35955bf0e528782
Signed-off-by: Thomas Fleury <tfleury@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/2207384
Reviewed-by: svc-mobile-coverity <svc-mobile-coverity@nvidia.com>
GVS: Gerrit_Virtual_Submit
Reviewed-by: Seema Khowala <seemaj@nvidia.com>
Reviewed-by: Vijayakumar Subbu <vsubbu@nvidia.com>
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>

userspace/units/fifo/nvgpu-fifo.c

@@ -110,7 +110,6 @@ int test_fifo_init_support(struct unit_module *m, struct gk20a *g, void *args)
 	gv11b_init_hal(g);
 	g->ops.fifo.init_fifo_setup_hw = NULL;
 	g->ops.gr.init.get_no_of_sm = stub_gv11b_gr_init_get_no_of_sm;
-	g->ops.tsg.init_eng_method_buffers = NULL;
 
 	global_m = m;
 
@@ -122,6 +121,7 @@ int test_fifo_init_support(struct unit_module *m, struct gk20a *g, void *args)
 	 */
 	g->ops.userd.setup_sw = stub_userd_setup_sw;
 #endif
+	g->ops.mm.init_mm_support(g);
 
 	err = nvgpu_fifo_init_support(g);
 	if (err != 0) {