x86: fix compile error for !CONFIG_MULTIBOOT

Some code was previously removed regarding elf notes. However,
that code left a dangling comma under !CONFIG_MULTIBOOT
configs for inline assembly constraints. Instead, place the comma
within the #ifdef stanza.

Change-Id: I805453ef57d34fbfb904b4d145d8874921d8d660
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/56844
Reviewed-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-by: David James <davidjames@chromium.org>
Reviewed-on: http://review.coreboot.org/4207
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>

src/arch/x86/boot/boot.c

@@ -20,9 +20,9 @@ void jmp_to_elf_entry(void *entry, unsigned long unused1, unsigned long unused2)
 		"	cld	\n\t"
 
 		::
-		"r" (entry),
+		"r" (entry)
 #if CONFIG_MULTIBOOT
-		"b"(mbi), "a" (MB_MAGIC2)
+		, "b"(mbi), "a" (MB_MAGIC2)
 #endif
 		);
 }