ARM: dts: msm: face detection add speed levels on MSM8994

Face detection should support different operating clock
frequencies. In face detection device they are defined as
clock rates levels. This change adds lower operating
clock frequencies. They can be selected as speed levels
based on driver needs.

Change-Id: I5edbe4c7163f7f1405803970526c333346ef2b7e
Signed-off-by: Gjorgji Rosikopulos <grosik@codeaurora.org>