[SCTP]: Fix sctp_assoc_seq_show() panics on big-endian systems.
This patch corrects the panic by casting the argument to the
pointer of correct size. On big-endian systems we ended up loading
only 32 bits of data because we are treating the pointer as an int*.
By treating this pointer as loff_t*, we'll load the full 64 bits
and then let regular integer demotion take place which will give us
the correct value.