Fix cifs_uniqueid_to_ino_t() function for s390x

This issue is caused by commit 02323db1 ("cifs: fix
cifs_uniqueid_to_ino_t not to ever return 0"), when BITS_PER_LONG
is 64 on s390x, the corresponding cifs_uniqueid_to_ino_t()
function will cast 64-bit fileid to 32-bit by using (ino_t)fileid,
because ino_t (typdefed __kernel_ino_t) is int type.

It's defined in arch/s390/include/uapi/asm/posix_types.h

    #ifndef __s390x__

    typedef unsigned long   __kernel_ino_t;
    ...
    #else /* __s390x__ */

    typedef unsigned int    __kernel_ino_t;

So the #ifdef condition is wrong for s390x, we can just still use
one cifs_uniqueid_to_ino_t() function with comparing sizeof(ino_t)
and sizeof(u64) to choose the correct execution accordingly.

Signed-off-by: Yadan Fan <ydfan@suse.com>
CC: stable <stable@vger.kernel.org>
Signed-off-by: Steve French <smfrench@gmail.com>