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/MAINTAINERS b/MAINTAINERS
index 868d4e1..af5a1fe 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -602,6 +602,7 @@
 F:	drivers/serial/serial_zynq.c
 F:	drivers/reset/reset-zynqmp.c
 F:	drivers/rtc/zynqmp_rtc.c
+F:	drivers/soc/soc_xilinx_zynqmp.c
 F:	drivers/spi/zynq_qspi.c
 F:	drivers/spi/zynq_spi.c
 F:	drivers/timer/cadence-ttc.c