ACPI video: Harden video bus adding.

It is always better to check return values, so add some new checks and
correct existing ones.

v2: Be consistent and don't mix errors from -E* and AE_* namespaces.

Signed-off-by: Igor Murzov <e-mail@date.by>
Signed-off-by: Len Brown <len.brown@intel.com>