drm/amdgpu/powerplay: hwmgr - modify the return value

Return value should be -EINVAL rather than EINVAL

Fixes: f83a9991("drm/amd/powerplay: add Vega10 powerplay support (v5)")
Fixes: 2cac05de("drm/amd/powerplay: add the hw manager for vega12 (v4)")
Cc: Eric Huang <JinHuiEric.Huang@amd.com>
Cc: Evan Quan <evan.quan@amd.com>
Reviewed-by: Evan Quan <evan.quan@amd.com>
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Xiaoliang Pang <dawning.pang@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>