i.MX: Fix FEC code for ECR register reset value.

According to the FEC chapter of i.MX25 reference manual ECR register is
initialized at 0xf0000000 at reset time.

We fix the value.

Signed-off-by: Jean-Christophe Dubois <jcd@tribudubois.net>
Signed-off-by: Jason Wang <jasowang@redhat.com>
