soc: xilinx: versal-net: Add soc_xilinx_versal_net driver

Add soc_xilinx_versal_net driver to identify the family & revision of
versal-net SoC. Add Kconfig option CONFIG_SOC_XILINX_VERSAL_NET to
enable/disable this driver. To enable this driver by default, add this
config to xilinx_versal_net_virt_defconfig file. This driver will be
probed using platdata U_BOOT_DEVICE structure which is specified in
mach-versal-net/cpu.c.

Signed-off-by: Michal Simek <michal.simek@amd.com>
Signed-off-by: Ashok Reddy Soma <ashok.reddy.soma@amd.com>
Link: https://lore.kernel.org/r/613d6bcffd9070f62cf348079ed16c120f8fc56f.1668612993.git.michal.simek@amd.com