m32r: convert to generic helpers for IPI function calls

This converts m32r to use the new helpers for smp_call_function() and
friends, and adds support for smp_call_function_single(). Not tested,
not even compiled.

Cc: Hirokazu Takata <takata@linux-m32r.org>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>