sbc8560: proper definitions for TSEC.

The definitions for the TSEC have become out of date.  There is no
longer any such options like "CONFIG_MPC85xx_TSEC1" or similar.
Update to match those of other boards, like the MPC8560ADS.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Acked-by: Ben Warren <biggerbadderben@gmail.com>