PM / devfreq: Revert addition of devfreq_governor_data and related changes

This reverts commit 0e5b3352 and fixes
other code that resulted from it. The devfreq_governor_data field is not
needed since the governors can use other means (like container_of) to find
out device specific private data

Change-Id: Ib7e5db29b40d9676bbb5cf6057e0072665ace821
Signed-off-by: Saravana Kannan <skannan@codeaurora.org>