Thanks to preceding cleanup steps, pcim_release() is now not needed
anymore and can be replaced by pcim_disable_device(), which is the exact
counterpart to pcim_enable_device().

This permits removing further parts of the old PCI devres implementation.

Replace pcim_release() with pcim_disable_device().  Remove the now unused
function get_pci_dr().  Remove the struct pci_devres from pci.h.

Link: https://lore.kernel.org/r/20240613115032.29098-12-pstanner@redhat.comSigned-off-by: Philipp Stanner <pstanner@redhat.com>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>