usb: xhci: Restore xhci_pci support for Renesas HCs

usb: xhci: Restore xhci_pci support for Renesas HCs

Some Renesas HCs require firmware upload to work, this is handled by the
xhci_pci_renesas driver. Other variants of those chips load firmware from
a SPI flash and are ready to work with xhci_pci alone.

A refactor merged in v6.12 broke the latter configuration so that users
are finding their hardware ignored by the normal driver and are forced to
enable the firmware loader which isn't really necessary on their systems.

Let xhci_pci work with those chips as before when the firmware loader is
disabled by kernel configuration.

Fixes: 25f51b76f90f ("xhci-pci: Make xhci-pci-renesas a proper modular driver")
Cc: stable <stable@kernel.org>
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=219616
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=219726
Signed-off-by: Michal Pecio <michal.pecio@gmail.com>
Tested-by: Nicolai Buchwitz <nb@tipi-net.de>
Link: https://lore.kernel.org/r/20250128104529.58a79bfc@foxbook
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>