Unchecked AcpiEvaluateObject return in acpi_panasonic_hkey_event causes NULL-deref panic

Summary

acpi_panasonic_hkey_event calls AcpiEvaluateObject for HINF never checks return. On failure buf.Pointer NULL res->Type(:405) NULL-deref panic. Line :420 if(buf.Pointer)AcpiOsFree proves author knew buf.Pointer could be NULL but check too late. Triggered by ACPI notify 0x80 when Panasonic hotkey(Fn+F1-F10) pressed. Less severe than sinf requires ACPI event not sysctl read.