net: sctp: outqueue: simplify sctp_outq_uncork function

Just a minor edit to simplify the function. No need for this
error variable here.

Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>