arm: add _end symbol to bootblock.ld

It's helpful to view program size by inspecting the symbols.
_start and _end exist on romstage and ramstage. In order to
be consistent add _end for bootblock too.

BUG=None
BRANCH=None
TEST=Built and noted bootblock has _end symbol.

Change-Id: I06634b317e957e8271bf32530a56b5541c79b9ee
Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Original-Commit-Id: b4ac926b30749d22e90a6f12ebac52107e241526
Original-Change-Id: I7f0b4dd4078c7d23c70949563b4c3f4df9e66142
Original-Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/210832
Original-Reviewed-by: Furquan Shaikh <furquan@chromium.org>
Reviewed-on: http://review.coreboot.org/8824
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

src/arch/arm/bootblock.ld

@@ -47,6 +47,7 @@ SECTIONS
 		*(.bss.*);
 		*(.sbss);
 		*(.sbss.*);
+		_end = .;
 	} : to_load = 0xff
 
 	preram_cbmem_console = CONFIG_CONSOLE_PRERAM_BUFFER_BASE;