gpu: nvgpu: unit: add VM unit tests

Add VM unit tests for the following requirements:
   - NVGPU-RQCD-45.C1: A valid GPU virtual address is/is not generated
     for the buffer passed into nvgpu_vm_map().
   - NVGPU-RQCD-45.C2: When a GPU virtual address is passed into the
     nvgpu_vm_map() function the resulting GPU virtual address of the
     map does/does not match the requested GPU virtual address.

JIRA NVGPU-1927

Change-Id: I7c9f7204772a611ff7baa56b6434a70d5b70cd27
Signed-off-by: Adeel Raza <araza@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/2036213
Reviewed-by: Philip Elcan <pelcan@nvidia.com>
Reviewed-by: Alex Waterman <alexw@nvidia.com>
Reviewed-by: Nicolas Benech <nbenech@nvidia.com>
GVS: Gerrit_Virtual_Submit
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>

userspace/include/unit/unit-requirement-ids.h

@@ -37,4 +37,6 @@
 
 #define PAGE_TABLE_REQ1_UID		"6439094"
 
+#define VM_REQ1_UID			"6434840"
+
 #endif