gianfar: Remove useless HAS_PADDING device flag

The RCTRL updates of the FSL_GIANFAR_DEV_HAS_PADDING device
flag get overriden by the FSL_GIANFAR_DEV_HAS_TIMER flag
settings, which impose a Rx padding alignment of 8 bytes.
As all the eTSEC devices that set HAS_PADDING also set the
HAS_TIMER flag, the HAS_PADDING flag is now obsolete.

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