ANDROID: sdcardfs: add parent pointer into dentry name hash

Fix following sdcardfs compilation error introduced in code
refactoring by upstream commit 8387ff25 ("vfs: make the
string hashes salt the hash").

  CC [M]  fs/sdcardfs/dentry.o
In file included from ./include/linux/dcache.h:13:0,
                 from fs/sdcardfs/sdcardfs.h:29,
                 from fs/sdcardfs/dentry.c:21:
fs/sdcardfs/dentry.c: In function ‘sdcardfs_hash_ci’:
./include/linux/stringhash.h:38:51: error: expected expression before ‘)’ token
 #define init_name_hash(salt)  (unsigned long)(salt)
                                                   ^
fs/sdcardfs/dentry.c:138:9: note: in expansion of macro ‘init_name_hash’
  hash = init_name_hash();
         ^

Change-Id: I9feb6c075a7e953726954f5746fc009202d3121c
Signed-off-by: Amit Pundir <amit.pundir@linaro.org>