- Improve error handling, by explictly return zero for success, error otherwise
- WMI query command can have arbitrary input sized params
- WMI query command can have specific output sized params (0, 4, 128,..) byte

I like to go on here, but this is a rather intrusive change that should
be looked at first. I am sure the one or other thing can be done better or
there might be typo/bug somewhere.

This did not get any testing yet, only compile tested.

Next steps could be:
  - Eventually introduce hp_wmi_perform_{read,write}_query macros
  - Introduce new wireless query interface (0x1B)
  - more
Signed-off-by: Thomas Renninger <trenn@suse.de>
Signed-off-by: Matthew Garrett <mjg@redhat.com>
CC: linux-acpi@vger.kernel.org
CC: platform-driver-x86@vger.kernel.org