scsi: ufs-mediatek: Add UFS support for Mediatek SoC chips

[Stanley Chu <stanley.chu-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org>]

Hello,

This patch series adds UFS M-PHY and UFS host driver support in MediaTek chipsets.

In the meantime, re-factors ufshcd_get_pwr_dev_param in vendors' drivers. This function is for vendors to decide finally agreed attributes for power mode change if vendors define
their host capability in struct ufs_dev_params. Because it is using by both ufs-qcom and ufs-hisi and also used in ufs-mediatek in this series, simply re-factor it and then every vendors can reuse it.

Changes since v5:
-	phy-mtk-ufs: Change mphy_readl/mphy_writel() to inline functions.
-	Fix typo in cover letter.

Changes since v4:
-	phy-mtk-ufs:
	  * Sort name in Kconfig and Makefile
	  * Drop "inline" and fix symbol name for mphy_set_bit()/mphy_clr_bit().
-	dt-bindings: phy-mtk-ufs: Drop "-clk" in clock names.
-	dt-bindings: ufs-mediatek:
	  * Change clock name "ufs-clk" to "ufs".
	  * Drop vcc related first. VCC control is planned to be added back by another patch accompanied with VCC/ICC logic fix in ufs common driver.

Changes since v3:
-	dt-bindings: Use specific compatible name for both ufs-mediatek and phy-mtk-ufs, remove interrupt-parent and lanes-per-direction in ufs-mediatek, and fix descriptions.

Changes since v2:
-	Fix header style with SPDX-License-Identifier declaration used.
-	Simplify ufs-phy-mtk to single source file since we has one MPHY version now, and do fixes according to Chunfeng Yun's comments.
-	Add dt-bindings of ufs-phy-mtk.

Changes since v1:
-	Re-factor ufshcd_get_pwr_dev_param in mediatek/qcom/hisi vendor drivers.
-	Introduce ufs-phy-mtk to have a good extension capability for different power control flows in future different MPHY versions.
-	Bind ufs-phy-mtk and hook suitable callbacks in ufs-mediatek driver.
-	Use PA_LOCAL_TX_LCC_ENABLE attribute defined in unipro.h instead.
-	Do some minor format fixes.