platform/x86: hp-wmi: Refactor redundant HPWMI_READ functions

Several functions perform the same WMI read int with different query
arguments. Refactor this into a single hp_wmi_read_int function.

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