ACPI: Remove acpi_pci_slot_init() headers from internal.h

Since acpi_pci_slot_init() is now called from acpi_pci_init()
and pci-acpi.h contains its header, remove that header (and the
empty definition of that function for CONFIG_ACPI_PCI_SLOT unset)
from internal.h as it doesn't have to be there any more.  That also
avoids a build warning about duplicate function definitions for
CONFIG_ACPI_PCI_SLOT unset.
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/internal.h

@@ -26,11 +26,6 @@
 acpi_status acpi_os_initialize1(void);
 int init_acpi_device_notify(void);
 int acpi_scan_init(void);
-#ifdef	CONFIG_ACPI_PCI_SLOT
-void acpi_pci_slot_init(void);
-#else
-static inline void acpi_pci_slot_init(void) { }
-#endif
 void acpi_pci_root_init(void);
 void acpi_pci_link_init(void);
 void acpi_pci_root_hp_init(void);