sfc: introduce shutdown entry point in efx pci driver

sfc: introduce shutdown entry point in efx pci driver

Make the device inactive when the system shutdown callback has been
invoked. This is achieved by freezing the driver and disabling the
PCI bus mastering.

Co-developed-by: Martin Habets <habetsm.xilinx@gmail.com>
Signed-off-by: Martin Habets <habetsm.xilinx@gmail.com>
Signed-off-by: Pieter Jansen van Vuuren <pieter.jansen-van-vuuren@amd.com>
Acked-by: Edward Cree <ecree.xilinx@gmail.com>
Link: https://lore.kernel.org/r/20220906105620.26179-1-pieter.jansen-van-vuuren@amd.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>