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/gaisler/grsim/u-boot.lds b/board/gaisler/grsim/u-boot.lds
index b241cbc..c608284 100644
--- a/board/gaisler/grsim/u-boot.lds
+++ b/board/gaisler/grsim/u-boot.lds
@@ -134,7 +134,7 @@
 	. = ALIGN(16); /* to speed clearing of bss up */
 	}
 	__bss_end = . ;
-	__bss_end__ = . ;
+	__bss_end = . ;
 	PROVIDE (end = .);
 
 /* Relocated into main memory */