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>
diff --git a/arch/arm/include/asm/arch-zynqmp/sys_proto.h b/arch/arm/include/asm/arch-zynqmp/sys_proto.h
index f256c7d..ad28568 100644
--- a/arch/arm/include/asm/arch-zynqmp/sys_proto.h
+++ b/arch/arm/include/asm/arch-zynqmp/sys_proto.h
@@ -30,6 +30,7 @@
 	TCM_SPLIT,
 };
 
+int zynq_board_read_rom_ethaddr(unsigned char *ethaddr);
 unsigned int zynqmp_get_silicon_version(void);
 
 void psu_init(void);