powerpc/pci: export pcibios_free_controller()

Export pcibios_free_controller(), so it can be used by the cxl module to
free virtual PHBs.

Signed-off-by: Andrew Donnellan <[e-mail]>
Signed-off-by: Michael Ellerman <[e-mail]>

arch/powerpc/kernel/pci-common.c

···
 	if (phb->is_dynamic)
 		kfree(phb);
 }
+EXPORT_SYMBOL_GPL(pcibios_free_controller);
 
 /*
  * The function is used to return the minimal alignment