soc: xilinx: zynqmp: Add soc_xilinx_zynqmp driver

soc_xilinx_zynqmp driver allows identification of family & revision
of zynqmp SoC. This driver is selected by CONFIG_SOC_XILINX_ZYNQMP.
Add this config to xilinx_zynqmp_virt_defconfig file.
Probe this driver using platdata U_BOOT_DEVICE structure which is
specified in mach-zynqmp/cpu.c.

Signed-off-by: T Karthik Reddy <t.karthik.reddy@xilinx.com>
Reviewed-by: Ashok Reddy Soma <ashok.reddy.soma@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
diff --git a/configs/xilinx_zynqmp_virt_defconfig b/configs/xilinx_zynqmp_virt_defconfig
index a1b189c..2d06da3 100644
--- a/configs/xilinx_zynqmp_virt_defconfig
+++ b/configs/xilinx_zynqmp_virt_defconfig
@@ -160,6 +160,7 @@
 CONFIG_ARM_DCC=y
 CONFIG_XILINX_UARTLITE=y
 CONFIG_ZYNQ_SERIAL=y
+CONFIG_SOC_XILINX_ZYNQMP=y
 CONFIG_SPI=y
 CONFIG_ZYNQ_SPI=y
 CONFIG_ZYNQMP_GQSPI=y