make pciehp_acpi_get_hp_hw_control_from_firmware()

this_patch_makes_the_needlessly_global_pciehp_acpi_get_hp_hw_control_from_firmware_static

;)

Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Kristen Carlson Accardi <kristen.c.accardi@intel.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>