arm64: zynqmp: Add support for zynqmp automotive silicons

Remove silicon prefix. Automotive grade devices are using xazu instead
of xczu prefix.

The patch "fpga: xilinx: Check for substring in device ID validation"
(sha1: f72132673a)
enables this functionality for zynq devices that only substrings are
checked.
Unfortunately there is no way how to detect device grade that's why
this change is reasonable.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>

board/xilinx/zynqmp/zynqmp.c

@@ -260,10 +260,10 @@ int board_init(void)
 	if (current_el() != 3) {
 		static char version[ZYNQMP_VERSION_SIZE];
 
-		strncat(version, "xczu", 4);
+		strncat(version, "zu", 2);
 		zynqmppl.name = strncat(version,
 					zynqmp_get_silicon_idcode_name(),
-					ZYNQMP_VERSION_SIZE - 5);
+					ZYNQMP_VERSION_SIZE - 3);
 		printf("Chip ID:\t%s\n", zynqmppl.name);
 		fpga_init();
 		fpga_add(fpga_xilinx, &zynqmppl);