Replace __bss_end__ with __bss_end

Note this is a tree-wide change affecting multiple architectures.

At present we use __bss_start, but mostly __bss_end__. This seems
inconsistent and in a number of places __bss_end is used instead.

Change to use __bss_end for the BSS end symbol throughout U-Boot. This
makes it possible to use the asm-generic/sections.h file on all
archs.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/board/freescale/mx31ads/u-boot.lds b/board/freescale/mx31ads/u-boot.lds
index 5267729..4d1858b 100644
--- a/board/freescale/mx31ads/u-boot.lds
+++ b/board/freescale/mx31ads/u-boot.lds
@@ -84,7 +84,7 @@
 		__bss_start = .;
 		*(.bss)
 		 . = ALIGN(4);
-		__bss_end__ = .;
+		__bss_end = .;
 	}
 
 	/DISCARD/ : { *(.bss*) }