usb: xhci-mtk: remove unnecessary setting of has_ippc

Due to @has_ippc's default value is 0, no need set it again if fail
to get ippc base address

Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Link: https://lore.kernel.org/r/20210507021127.54717-2-chunfeng.yun@mediatek.com


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