fir a typo that caused up-sampling coefficiens to be wrong

up-sample coefficient were generated with a cut-off frequency of 24KHz
intead of ~20KHz, which caused more aliasing in the audible band.

also increased the attenuation to 1.3 dB on both up and down
sampling coefficient to avoid clipping.

Change-Id: Ie8aeecf1429190541b656810c6716b6aae5ece2e