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/sh/cpu/sh4/u-boot.lds b/arch/sh/cpu/sh4/u-boot.lds
index 0ecafcf..5721c18 100644
--- a/arch/sh/cpu/sh4/u-boot.lds
+++ b/arch/sh/cpu/sh4/u-boot.lds
@@ -92,5 +92,5 @@
 	}
 	PROVIDE (bss_end = .);
 
-	PROVIDE (__bss_end__ = .);
+	PROVIDE (__bss_end = .);
 }