usb: host: xhci-plat: Use dev_is_pci() helper

Use common dev_is_pci() helper for checking PCI devices.
And if CONFIG_PCI is not defined, dev_is_pci returns false. Therefore,
CONFIG_PCI is also unnecessary, so remove it.

Signed-off-by: Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp>
Link: https://lore.kernel.org/r/20230405234605.2310155-1-nobuhiro1.iwamatsu@toshiba.co.jp
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>