drm/amdgpu: Fix spelling mistake "initiailize" -> "initialize" and grammar

There is a spelling mistake and a grammatical error in a dev_err
message. Fix it.

Reviewed-by: Tao Zhou <tao.zhou1@amd.com>
Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>