wct4xxp: Allow vpm450m.c to compile against vanilla 2.6.18.

This adds definitions for bool and pr_fmt which are needed when compiling
against vanilla 2.6.18.

Signed-off-by: Shaun Ruffell <sruffell@digium.com>
Signed-off-by: Russ Meyerriecks <rmeyerriecks@digium.com>
(cherry picked from commit db040e5cd7004e6aad4074908f314235a4fc316d)