pci: Use debug() instead of DEBUGF() in pci_auto.c

This file does not need its own way of doing debug(). Clean it up to use the
new way.

Signed-off-by: Simon Glass <sjg@chromium.org>
Acked-by: Pavel Machek <pavel@denx.de>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>