arm64: zynqmp: Create description for generic SC (vpk120-revB)

arm64: zynqmp: Create description for generic SC (vpk120-revB)

System controllers are pretty much the same on the all boards that's why
use autodetection based on i2c eeprom. This should end up with having only
one BSP for all SCs with only DT overlays to cover different i2c
structures.

All MIOs are fixed by the spec that's why not a problem to description
pinctrl setting.

Apart from eth phy reset, it also set proper phy delays.
The TI DP83867 PHY datasheet says:
T1: Post RESET stabilization time == 195us
T3: Hardware configuration pins transition to output drivers == 64us
T4: RESET pulse width == 1us
So with a little overhead set 'reset-assert-us' to 100us (T4) and
'reset-deassert-us' to 280us (T1+T3).

NOTE: The tuning of TI DP83867 phy reset delay is derived from linux
upstream commit: 5dbadc848259(arm64: dts: fsl: add support for Kontron
pitx-imx8m board).

i2c structure on Xilinx Versal evaluation platforms contain a lot of
devices but also connection to connectors like SFP. Because of this
complicated structure with also all level shifters, i2c muxes, etc. not all
devices are able to reliably work on 400kHz even if they are compatible
with this speed. That's why set i2c frequency to 100KHz to increase
reliability of the i2c bus.

Signed-off-by: Michal Simek <michal.simek@amd.com>
Link: https://lore.kernel.org/r/c8092340f92144f0cc9096194198f227015bc013.1695808407.git.michal.simek@amd.com