fs_mgr: Switch to LOG()/PLOG() defined in <android-base/logging.h>

This is the minimal change just to replace KLOG_{INFO, WARNING, ERROR}
defined in <cutils/klog.h> to LOG()/PLOG() defined in
<android-base/logging.h>.

The logging.h uses program invocation name as the tag when logging.
e.g., init logs will have "init: ..." at the beginning in each line.
To facilitate debugging, this commit adds [libfs_mgr] after the tag,
and the resulting output will like this:

  [   11.278002] init: [libfs_mgr]Enabling dm-verity for system (mode 2)
  [   11.283309] init: [libfs_mgr]loading verity table: '1 /dev/block/platform/soc.0/f9824900.sdhci/by-name/system ...'
  [   11.337884] init: [libfs_mgr]Not running /system/bin/tune2fs on /dev/block/dm-0 (executable not in system image)
  [   11.362281] init: [libfs_mgr]__mount(source=/dev/block/dm-0,target=/system,type=ext4)=0
  [   11.376331] init: [libfs_mgr]Requested quota status is match on /dev/block/platform/soc.0/f9824900.sdhci/by-name/vendor
  [   11.398237] init: [libfs_mgr]__mount(source=/dev/block/platform/soc.0/f9824900.sdhci/by-name/vendor,target=/vendor,type=ext4)=0
  [   11.410735] init: [libfs_mgr]Requested quota status is match on /dev/block/platform/soc.0/f9824900.sdhci/by-name/userdata
  [   11.426783] init: [libfs_mgr]check_fs(): mount(/dev/block/platform/soc.0/f9824900.sdhci/by-name/userdata,/data,ext4)=-1: Invalid argument
  [   11.439154] init: [libfs_mgr]Running /system/bin/e2fsck on /dev/block/platform/soc.0/f9824900.sdhci/by-name/userdata

Bug: 34336098
Test: check device can boot

Change-Id: Idcbaca1050e2d8eabe1e4510a0af03aa0312d03a