UPSTREAM: kdb: use task_cpu() instead of task_thread_info()->cpu

commit e558af65be65713ef2e8b2aa637c6263caeed172 upstream.

We'll need this cleanup to make the cpu field in thread_info be
optional.

Link: http://lkml.kernel.org/r/da298328dc77ea494576c2f20a934218e758a6fa.1468523549.git.luto@kernel.org


Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Change-Id: I0cd616f086f0eb54ed997ea153382fbf6188dba9
Signed-off-by: Amit Pundir <amit.pundir@linaro.org>