qcacld-3.0: Clean up remaining references of WLAN_POWER_DEBUGFS

Power stats is moved from debugfs to sysfs as part of commit
I10df003fe8f79d35d0758b56d971f4973d27750b and hence remove
the remaining references of WLAN_POWER_DEBUGFS.

Change-Id: Iba29387ab93740595560e068e4bd4ede8efafbc9
CRs-Fixed: 2661078
6 files changed