qcom-common: Update media_codecs.xml

Change-Id: I46ea61d3dcfe0e51891fa085ed1ff9d86bea728b
qcom-common: ondemand: Modify Sampling Down Factor to 2

Change needed to help improve frequency scaling
in ondemand governor. Sampling Down Factor
is set to 2 in the init.qcom.post_boot.sh

Change-Id: I1f8eb4fabce24ed7076251f2cc1ac96e8dc79dd4