gpu: nvgpu: add tests for circ_buf

Add unit tests for posix circ_buf unit.

Jira NVGPU-4417

Change-Id: Ic0b04961cdd7813aed6f9b16fd0724b0e3cfeb2a
Signed-off-by: ajesh <akv@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/c/linux-nvgpu/+/2287141
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>

userspace/required_tests.json

@@ -4142,6 +4142,18 @@
         "unit": "posix_bug",
         "test_level": 0
     },
+    {
+        "test": "test_circbufcnt",
+        "case": "circbufcnt",
+        "unit": "posix_circbuf",
+        "test_level": 0
+    },
+    {
+        "test": "test_circbufspace",
+        "case": "circbufspace",
+        "unit": "posix_circbuf",
+        "test_level": 0
+    },
     {
         "test": "test_cond_init_destroy",
         "case": "init",