arc: make sure _start is in the beginning of .text section

This is important to have entry point in the beginning of .text section
because it allows simple loading and execution of U-Boot.

For example pre-bootloader loads U-Boot in memory starting from offset
0x81000000 and then just jumps to the same address.

Otherwise pre-bootloader would need to find-out where entry-point is. In
its turn if it deals with binary image of U-Boot there's no way for
pre-bootloader to get required value.

Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
diff --git a/arch/arc/cpu/u-boot.lds b/arch/arc/cpu/u-boot.lds
index ccddbf7..693df74 100644
--- a/arch/arc/cpu/u-boot.lds
+++ b/arch/arc/cpu/u-boot.lds
@@ -13,6 +13,7 @@
 	.text :	{
 		*(.__text_start)
 		*(.__image_copy_start)
+		arch/arc/lib/start.o (.text*)
 		*(.text*)
 	}