vsprintf: clarify comments for printf_spec flags

Add clues about what the SMALL and SPECIAL flags do.
Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

lib/vsprintf.c

@@ -381,8 +381,8 @@ static noinline char *put_dec(char *buf, unsigned long long num)
 #define PLUS	4		/* show plus */
 #define SPACE	8		/* space if plus */
 #define LEFT	16		/* left justified */
-#define SMALL	32		/* Must be 32 == 0x20 */
-#define SPECIAL	64		/* 0x */
+#define SMALL	32		/* use lowercase in hex (must be 32 == 0x20) */
+#define SPECIAL	64		/* prefix hex with "0x", octal with "0" */
 
 enum format_type {
 	FORMAT_TYPE_NONE, /* Just a string part */