net: phy: mediatek: Add token ring access helper functions in mtk-phy-lib

net: phy: mediatek: Add token ring access helper functions in mtk-phy-lib

This patch adds TR(token ring) manipulations and adds correct
macro names for those magic numbers. TR is a way to access
proprietary registers on page 52b5. Use these helper functions
so we can see which fields we're going to modify/set/clear.

TR functions with __* prefix mean that the operations inside
aren't wrapped by page select/restore functions.

This patch doesn't really change registers' settings but just
enhances readability and maintainability.

Signed-off-by: Sky Huang <skylake.huang@mediatek.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://patch.msgid.link/20250213080553.921434-3-SkyLake.Huang@mediatek.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>