tc35815: Fix receiver hangup on Rx FIFO overflow

On Rx FIFO overflow error, the controller consume a buffer descriptor
but currently the driver does not give it back to the controller.
This results unrecoverable 'Buffer List Exhausted' condition.  This
patch fix this problem by moving a "fbl_count--" line to proper place.

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>