mpc83xx: Fix PCI, USB, bootargs for MPC8349E-mITX

PREREQUISITE PATCHES:

* This patch can only be applied after the following patches have been applied:

  1) DNX#2006092142000015 "Add support for the MPC8349E-mITX  1/2"
  2) DNX#2006092142000024 "Add support for the MPC8349E-mITX  2/2"

CHANGELOG:

* For the 8349E-mITX, fix some size values in pci_init_board(), enable
  the clock for the 2nd USB board (Linux kernel will hang otherwise),
  and fix the CONFIG_BOOTARGS macro.

Signed-off-by: Timur Tabi <timur@freescale.com>