parisc: unaligned: Include linux/sysctl.h for unaligned_enabled

Fix sparse warning that unaligned_enabled wasn't declared.
Signed-off-by: Helge Deller <deller@gmx.de>

arch/parisc/kernel/unaligned.c

@@ -11,6 +11,7 @@
 #include <linux/signal.h>
 #include <linux/ratelimit.h>
 #include <linux/uaccess.h>
+#include <linux/sysctl.h>
 #include <asm/unaligned.h>
 #include <asm/hardirq.h>
 #include <asm/traps.h>