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/woodburn/woodburn.c b/board/woodburn/woodburn.c
index 5b044a9..7c36af0 100644
--- a/board/woodburn/woodburn.c
+++ b/board/woodburn/woodburn.c
@@ -148,7 +148,7 @@
 	woodburn_init();
 
 	/* Clear the BSS. */
-	memset(__bss_start, 0, __bss_end__ - __bss_start);
+	memset(__bss_start, 0, __bss_end - __bss_start);
 
 	/* Set global data pointer. */
 	gd = &gdata;