usb: xhci-mtk: remove declaration of xhci_mtk_setup()

Move xhci_driver_overrides struct variable after definition
of xhci_mtk_setup(), then we can remove it's declaration.

Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Link: https://lore.kernel.org/r/cf627d611a5c59508371cc3360cb402b70825fd8.1615170625.git.chunfeng.yun@mediatek.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>