amcs: update CCA sysfs

Rename cca_rate_read_once to cca_count_read_once
Ex:
 cat /sys/devices/platform/audiometrics/cca_count_read_once_show
 Ex: result 10 15 20 25
  means active CCA are 10, 15, 20, and 25

Bug: 289857250
Test: local testing
Change-Id: I20ab587395adb89bb66aeb898154b107f5c9a518
2 files changed