gianfar: Remove redundant programming of [rt]xic registers

For Multi Q Multi Group (MQ_MG_MODE) mode, the Rx/Tx colescing registers [rt]xic
are aliased with the [rt]xic0 registers (coalescing setting regs for Q0). This
avoids programming twice in a row the coalescing registers for the Rx/Tx hw Q0.

Signed-off-by: Claudiu Manoil <claudiu.manoil@freescale.com>
Signed-off-by: David S. Miller <davem@davemloft.net>