sdcard: Properly handle deleted nodes

The sdcard fuse deamon is not properly handling deleted nodes that are
still in use (opened by some process). Typically Linux filesystems makes
it possible to open a file, unlink it and then still use it. In case of a
storage emulated by sdcard deamon this does not work as expected - other
process are not able to recreate file/dir with the same name until all
references to deleted file are closed.

The easiest way to trigger this problem is:

process1: mkdir /sdcard/test1; cd /sdcard/test1
process2: rm -r /sdcard/test1
process2: mkdir /sdcard/test1

After that, process2 will get an error:
mkdir failed for /sdcard/test1, Device or resource busy

There is exactly the same problem with files as directories.
This may case issues for example with directories that are
automatically recreated when they are missing (like DCIM directory). If
some process holds file opened inside of such directory but that
directory is removed, process trying to recreate the directory will get
EBUSY error and possibly crash.

Verified on the Z Ultra GPE.

Change-Id: I1cbf0bec135e6aaafba0ce8e5bb594e3639e0007