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/arch/nds32/cpu/n1213/start.S b/arch/nds32/cpu/n1213/start.S
index 889bf8b..558fd0e 100644
--- a/arch/nds32/cpu/n1213/start.S
+++ b/arch/nds32/cpu/n1213/start.S
@@ -240,7 +240,7 @@
 clear_bss:
 	la	$r0, __bss_start	/* r0 <- rel __bss_start in FLASH */
 	add	$r0, $r0, $r9		/* r0 <- rel __bss_start in FLASH */
-	la	$r1, __bss_end__	/* r1 <- rel __bss_end in RAM */
+	la	$r1, __bss_end		/* r1 <- rel __bss_end in RAM */
 	add	$r1, $r1, $r9		/* r0 <- rel __bss_end in RAM */
 	li	$r2, 0x00000000		/* clear */