galileo: add missing configure call for PWM0

If PWM had been configured by some other application after the last
power cycle, it would appear to work fine. However, an application using
PWM loaded right after a power cycle would not work, since the configure
call was missing during boot.

Change-Id: I389ca2122e1a4a7ea6d298efb327438761336d75
Work-by: Mike Hirst <michael.hirst@windriver.com>
Signed-off-by: Benjamin Walsh <benjamin.walsh@windriver.com>