allow using custom recovery_ui.c

Change-Id: Ib89c3fc7783dcb384af0964892ce5b200f5433a5
mounts: add find_mounted_volume_by_real_node
this function finds a mounted volume by the real device node(resolved symlink)

Change-Id: Iff28cf7dd088f73248e23d99bf321f2bb61e1cc2