pci: Remove CONFIG_PCI_ENUM_ONLY as it's not used (any more)

pci: Remove CONFIG_PCI_ENUM_ONLY as it's not used (any more)

This patch completely removes CONFIG_PCI_ENUM_ONLY from the PCI code as
it is not configured for any board (any more). With this removal, some
PCI related files get cleaned up a bit.

Additional, dm_pciauto_setup_device() is now static, as it's not
referenced from any code outside of this C file.

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Simon Glass <sjg@chromium.org>
Cc: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>