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/arm/cpu/arm926ejs/davinci/spl.c b/arch/arm/cpu/arm926ejs/davinci/spl.c
index 714fa92..ca8a412 100644
--- a/arch/arm/cpu/arm926ejs/davinci/spl.c
+++ b/arch/arm/cpu/arm926ejs/davinci/spl.c
@@ -64,7 +64,7 @@
 #endif
 
 	/* Third, we clear the BSS. */
-	memset(__bss_start, 0, __bss_end__ - __bss_start);
+	memset(__bss_start, 0, __bss_end - __bss_start);
 
 	/* Finally, setup gd and move to the next step. */
 	gd = &gdata;