cpufreq: msm: fix race in cpufreq

__cpufreq_driver_target expects to be called with the rw semaphore
held. We are not doing this when the frequency is asked to be changed
by dcvs.

Use cpufreq_driver_target variant of that function which gets the
rw semaphore before setting the frequency.

Change-Id: I67a7d437f68749f43c26b95ae73f436890326019
Signed-off-by: Abhijeet Dharmapurikar <adharmap@codeaurora.org>