platform/x86: hp-wmi: Cleanup local variable declarations

Declare like types on one line. Order declarations in decreasing length
where possible.

Signed-off-by: Darren Hart (VMware) <dvhart@infradead.org>
Tested-by: Carlo Caione <carlo@endlessm.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>