PM / devfreq: fix find_governor_data() function

find_governor_data() was added to the devfreq infrastructure earlier.
It uses an incorrect condition in an if-statement when it searches
a governor by its name. Fixing the condition.

Change-Id: Ib297caad3e23984651217a43d2fdde1f6fcbdf7a
Signed-off-by: Vladimir Razgulin <vrazguli@codeaurora.org>