Blackfin: use raw_smp_processor_id() in exception code

When preempt debugging is enabled, smp_processor_id() may utilize the
"current" structure.  This may not be safe to access under all exceptions
due to it being in dynamically allocated memory.  So in exception code,
make sure we use raw_smp_processor_id() instead to get at the real value
directly.

Signed-off-by: Yi Li <yi.li@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>