phy: mediatek: pcie: use new helper to update register bits

The new helper will use FIELD_PREP() macro to prepare bits value
according to mask, then we no need do it anymore.

Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20220920090038.15133-6-chunfeng.yun@mediatek.com


Signed-off-by: Vinod Koul <vkoul@kernel.org>