phy: mediatek: mipi: mt8173: use common helper to access registers

Use MediaTek phy's common helper to access registers, then we can remove
mipi-dsi's I/O helpers.

Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20220920090038.15133-16-chunfeng.yun@mediatek.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

phy: mediatek: mipi: mt8173: use FIELD_PREP to prepare bits field

Use FIELD_PREP() macro to prepare bits field value, then no need define
macros of bits offset.

Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20220920090038.15133-15-chunfeng.yun@mediatek.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

phy: mediatek: mipi: mt8173: use GENMASK to generate bits mask

Use GENMASK() macro to generate bits mask

Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20220920090038.15133-14-chunfeng.yun@mediatek.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

phy: mediatek: Move mtk_mipi_dsi_phy driver into drivers/phy/mediatek folder

mtk_mipi_dsi_phy is currently placed inside mediatek drm driver, but it's
more suitable to place a phy driver into phy driver folder, so move
mtk_mipi_dsi_phy driver into phy driver folder.

Signed-off-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>
Acked-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Acked-by: Vinod Koul <vkoul@kernel.org>