Pixelstats: support all pca sysfs node paths for pca charge_stats

Because pca sysfs node change paths, need to be compatible with
all file paths.

Bug: 235050913
Test: check log in logcat
Signed-off-by: Jack Wu <wjack@google.com>
Change-Id: I7b5294e42bf13e2ebe84381441d9cb136c3b5dad