mpc8323erdb: define CONFIG_PCI_SKIP_HOST_BRIDGE

Commit 55774b51 broke the onboard USB
controller on the PCI bus in Linux on the MPC8323ERDB.

This fixes it by defining CONFIG_PCI_SKIP_HOST_BRIDGE in the board's
config file.

Signed-off-by: Michael Barkowski <michael.barkowski@freescale.com>
Signed-off-by: Kim Phillips <kim.phillips@freescale.com>