x86: Fix various code format issues in start16.S

Various minor code format issues are fixed in start16.S:
- U-boot -> U-Boot
- 32bit -> 32-bit
- Use TAB instead of SPACE to indent
- Move the indention location of the GDT comment block

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Simon Glass <sjg@chromium.org>

arch/x86/cpu/start16.S

@@ -1,5 +1,5 @@
 /*
- *  U-boot - x86 Startup Code
+ *  U-Boot - x86 Startup Code
  *
  * (C) Copyright 2008-2011
  * Graeme Russ, <graeme.russ@gmail.com>
@@ -49,7 +49,7 @@ o32 cs	lgdt	gdt_ptr
 	jmp	ff
 ff:
 
-	/* Finally restore BIST and jump to the 32bit initialization code */
+	/* Finally restore BIST and jump to the 32-bit initialization code */
 	movw	$code32start, %ax
 	movw	%ax, %bp
 	movl	%ecx, %eax