intel_scu_ipc: calculate divisor properly for osc clk

intel_scu_ipc: calculate divisor properly for osc clk

BZ: 26932

intel_scu_ipc_osc_clk() calculates incorrectly the clock divisor.
This affects at least camera with 9.6 MHz clock in Clovertrail.
Fix it.

Change-Id: Ib35fa790346cb316288e5244f0d65d3b2accfcc4
Signed-off-by: Tuukka Toivonen <tuukka.toivonen@intel.com>
Reviewed-on: http://android.intel.com:8080/38189
Reviewed-by: Kruger, Jozef <jozef.kruger@intel.com>
Reviewed-by: Cohen, David A <david.a.cohen@intel.com>
Tested-by: Koski, Anttu <anttu.koski@intel.com>
Reviewed-by: Yang, Fei <fei.yang@intel.com>
Reviewed-by: Koski, Anttu <anttu.koski@intel.com>
Reviewed-by: buildbot <buildbot@intel.com>
Tested-by: buildbot <buildbot@intel.com>