cifs: Use ULL suffix for 64-bit constant

On 32-bit (e.g. with m68k-linux-gnu-gcc-4.1):

    fs/cifs/inode.c: In function ‘simple_hashstr’:
    fs/cifs/inode.c:713: warning: integer constant is too large for ‘long’ type

Fixes: 7ea884c7 ("smb3: Fix root directory when server returns inode number of zero")
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-by: Aurelien Aptel <aaptel@suse.com>