tsec: fix multiple PHY support

The change entitled "Reduce CONFIG_MPC8YXX_TSECx to CONFIG_TSECx"
broke multiple PHY support in tsec.c.  This fixes it.

Signed-off-by: Zach Sadecki <Zach.Sadecki@ripcode.com>
Signed-off-by: Kim Phillips <kim.phillips@freescale.com>