net: cpsw: remove redundant calls enabling dma interrupts.

The function, cpsw_intr_enable, already calls cpdma_ctlr_int_ctrl.  There
is no need to enable the dma interrupts twice.  This patch removes the
extra call.

Signed-off-by: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>