arm64: ptr auth: Move per-thread keys from thread_info to thread_struct

We don't need to get at the per-thread keys from assembly at all, so
they can live alongside the rest of the per-thread register state in
thread_struct instead of thread_info.

This will also allow straighforward whitelisting of the keys for
hardened usercopy should we expose them via a ptrace request later on.

Signed-off-by: Will Deacon <will.deacon@arm.com>

arch/arm64/include/asm/thread_info.h

@@ -28,7 +28,6 @@
 struct task_struct;
 
 #include <asm/memory.h>
-#include <asm/pointer_auth.h>
 #include <asm/stack_pointer.h>
 #include <asm/types.h>
 
@@ -55,9 +54,6 @@ struct thread_info {
 #endif
 		} preempt;
 	};
-#ifdef CONFIG_ARM64_PTR_AUTH
-	struct ptrauth_keys	keys_user;
-#endif
 };
 
 #define thread_saved_pc(tsk)	\