panic: add cpu/pid to warn_slowpath_common in WARNING printk()s

panic: add cpu/pid to warn_slowpath_common in WARNING printk()s

Add the cpu/pid that called WARN() so that the stack traces can be matched
up with the WARNING messages.

Signed-off-by: Alex Thorlton <athorlton@sgi.com>
Reviewed-by: Robin Holt <holt@sgi.com>
Cc: Stephen Boyd <sboyd@codeaurora.org>
Cc: Vikram Mulukutla <markivx@codeaurora.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>