smack: introduce a special case for tmpfs in smack_d_instantiate()

smack: introduce a special case for tmpfs in smack_d_instantiate()

Files created with __shmem_file_stup() appear to have somewhat fake
dentries which make them look like root directories and not get
the label the current process or ("*") star meant for tmpfs files.

Change-Id: Id97004f2a5090cee9c16778109d849d433bd39c9
Signed-off-by: Łukasz Stelmach <l.stelmach@samsung.com>
Signed-off-by: Seung-Woo Kim <sw0312.kim@samsung.com>
(cherry picked from commit 7141e6be730e637255b1c75789ca67d309cbce95)
Signed-off-by: Sooyoung Ha <yoosah.ha@samsung.com>