phy: ti: j721e-wiz: Implement DisplayPort mode to the wiz driver

For DisplayPort use we need to set WIZ_CONFIG_LANECTL register's
P_STANDARD_MODE bits to "mode 3". In the DisplayPort use also the
P_ENABLE bits of the same register are set to P_ENABLE instead of
P_ENABLE_FORCE, so that the DisplayPort driver can enable and disable
the lane as needed. The DisplayPort mode is selected according to
"cdns,phy-type"-properties found in link subnodes under the managed
serdes (see "ti,sierra-phy-t0" and "ti,j721e-serdes-10g" devicetree
bindings for details). All other values of "cdns,phy-type"-property
but PHY_TYPE_DP will set P_STANDARD_MODE bits to 0 and P_ENABLE bits
to force enable.

Signed-off-by: Jyri Sarha <jsarha@ti.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>