[PATCH] m32r: Fix smp.c for preempt kernel

This patch fixes the following BUG message of arch/m32r/smp.c for
CONFIG_DEBUG_PREEMPT:

BUG: using smp_processor_id() in preemptible

This message is displayed by an smp_processor_id() execution during
kernel's preemptible-state.

Signed-off-by: Hitoshi Yamamoto <hitoshiy@isl.melco.co.jp>
Signed-off-by: Hirokazu Takata <takata@linux-m32r.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>