Refactor lvm:filter logic

  * Apply filter, only if something has been passed
  * lvm support lvm.conf check - lets use it!
  * Changes in lvm.conf must be
    reflected in initramfs => add corresponding trigger

Prod-related: PROD-26396 (PROD:26396)

Change-Id: I7055f78db52773cbf7d4f11e255110ca9053f4be
2 files changed