PCI: Unexport pci_bus_sem

pci_bus_sem is not used by a loadable kernel module and does not need to be
exported.

It was exported by ce29ca3e ("PCI: acpiphp: remove all functions in
slot, even without ACPI _EJx"), which added a use of pci_bus_sem in
acpiphp, which could be built as a module at that time.  But since
6037a803 ("PCI: acpiphp: Convert acpiphp to be builtin only, not
modular"), it can no longer be built as a module.

Link: https://lore.kernel.org/r/20190718032951.40188-1-skunberg.kelsey@gmail.comSigned-off-by: Kelsey Skunberg <skunberg.kelsey@gmail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

drivers/pci/search.c

@@ -15,7 +15,6 @@
 #include "pci.h"
 
 DECLARE_RWSEM(pci_bus_sem);
-EXPORT_SYMBOL_GPL(pci_bus_sem);
 
 /*
  * pci_for_each_dma_alias - Iterate over DMA aliases for a device