msm: kgsl: Move OPP disabling after probe

Since we cannot manipulate the OPP table during probe
due to the use of a mutex, move the disabling of
unused OPP levels to the first time we are
powering up.

Change-Id: I19dd4e038a2380bfb9f18560f8456f84ec3027d2
Signed-off-by: Kyle Piefer <kpiefer@codeaurora.org>
Signed-off-by: Oleg Perelet <operelet@codeaurora.org>
Signed-off-by: Carter Cooper <ccooper@codeaurora.org>