ARM: dts: msm: Add max codec aux devs property for sm6150

Add codec-max-aux-devs property under sm6150 sound
node to identify the maximum number of auxilary
codec devices supported for a target.

Change-Id: Ief6958f377f062b44ea525db213f1dbd3127dbe2
Signed-off-by: Aditya Bavanari <abavanar@codeaurora.org>