[PATCH] alpha: task_thread_info()

use task_thread_info() for accesses to thread_info of task in arch/alpha
and include/asm-alpha

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>