msm: kgsl: Fix circular dependency between KGSL and devfreq

If QCOM_SCM happens to not be selected we get into a funky little loop
between the devfreq governor and the KGSL driver since they depend on
each other.  Solve it by making KGSL always use QCOM_SCM (because it
does) and remove the dependency on QCOM_SCM from the governor and just
let it depend entirely on KGSL.

Change-Id: Ic0dedbadd703dcdb1e78a896585760132045cdf1
Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>