drivers/pci: Fix for debug builds without CONFIG_PCI_ENUM_ONLY

The debug printing references bar_res, which exists only if
CONFIG_PCI_ENUM_ONLY is not defined. Therefore move it into the ifdef'd
area.

Signed-off-by: Phil Sutter <phil@nwl.cc>
Acked-by: Stefan Roese <sr@denx.de>
Reviewed-by: Tom Rini <trini@konsulko.com>