fec: fix definition of 5272 version of FEC_X_DES_ACTIVE register

fec: fix definition of 5272 version of FEC_X_DES_ACTIVE register

The ColdFire 5272 FEC driver has a different register address map
than other users of the FEC driver. And its definition of the
FEC_X_DES_ACTIVE register is incorrect, it should be 0x14.
The fec interface cannot transmit data with the old value.

Signed-off-by: Greg Ungerer <gerg@uclinux.org>
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Signed-off-by: David S. Miller <davem@davemloft.net>