tests/amdgpu: Stop the amdgpu test when device initialize failed

The amdgpu test should be stopped when amdgpu device inialize failed.

Otherwise, the amdgpu test will be executed and get wrong result.

For example, for the command "./amdgpu_test -l", all of the test cases

status will show as enabled.

Signed-off-by: Ma Jun majun@amd.com

Reviewed-by: Veerabadhran Gopalakrishnan Veerabadhran.Gopalakrishnan@amd.com