PowerHal: move power HAL property to PRODUCT_VENDOR_PROPERTIES

'vendor.powerhal.adpf.rate' should be placed in /vendor if it is used
by vendor processes. The product partition (and system_ext) belongs to
"system" in Treble view so it will be replaced by GSI.

Bug: 204035997
Test: Install GSI by b/204035997#comment19 and run the following
      command would get a non-null number:
      $ adb root; adb shell getprop vendor.powerhal.adpf.rate
Test: $ adb shell 'find . -type f -name "build.prop" -exec grep -Hn "adpf" {} \; 2> /dev/null'
    ./vendor/build.prop:83:vendor.powerhal.adpf.rate=16666666
Change-Id: I10c8f55609aff49e32b2bc6dc7474f8bafb116e9
2 files changed