microblaze: Guard __HAVE_ARCH macros with __KERNEL__ in string.h

A polarity reversal in the __KERNEL__ guard prevents the __HAVE_ARCH
flags from being defined in kernel compilation.

I noticed that there's now an option for assembly-optimized versions of
memcpy and memmove. I believe this may be buggy; when I turn it on, all
my printk output gets smashed together, as if the newlines aren't getting
copied.
Signed-off-by: NSteven J. Magnani <steve@digidescorp.com>
Signed-off-by: NMichal Simek <monstr@monstr.eu>

arch/microblaze/include/asm/string.h

@@ -9,7 +9,7 @@
 #ifndef _ASM_MICROBLAZE_STRING_H
 #define _ASM_MICROBLAZE_STRING_H
 
-#ifndef __KERNEL__
+#ifdef __KERNEL__
 
 #define __HAVE_ARCH_MEMSET
 #define __HAVE_ARCH_MEMCPY