ACPI: rearrange acpi_pci_bind/acpi_pci_unbind in pci_bind.c

This is a pure code movement patch that does $subject in order
to make the following patch easier to read and review.

No functional change.

Signed-off-by: Alex Chiang <achiang@hp.com>
Signed-off-by: Len Brown <len.brown@intel.com>