msm: ipa: scale IPA clocks without lock

In order to reduce ping RTT, IPA clock scaling should not
be called with a mutex lock. This optimization will allow to faster
obtain a reference to IPA clocks

Change-Id: Ibd4c24255ff4ce7586f892e501a737294ec40b2f
CRs-Fixed: 1098689
Acked-by: Ady Abraham <adya@qti.qualcomm.com>
Signed-off-by: Skylar Chang <chiaweic@codeaurora.org>