p1: config: use tiny rcu

This option selects the RCU implementation that is
designed for UP systems from which real-time response
is not required.  This option greatly reduces the
memory footprint of RCU.

Signed-off-by: Humberto Borba <humberos@gmail.com>
Change-Id: Ic27561955d5dbbc4a1f69603e45e68a756a06d34