arm64: zynqmp: Add missing zynq_board_read_rom_ethaddr() prototype

Add missing zynq_board_read_rom_ethaddr() prototype reported by sparse.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Reviewed-by: Joe Hershberger <joe.hershberger@ni.com>

arch/arm/include/asm/arch-zynqmp/sys_proto.h

@@ -30,6 +30,7 @@ enum {
 	TCM_SPLIT,
 };
 
+int zynq_board_read_rom_ethaddr(unsigned char *ethaddr);
 unsigned int zynqmp_get_silicon_version(void);
 
 void psu_init(void);