powerpc/85xx: TQM8548: update defconfig

Enable highmem support for the TQM8548-AG modules and NAND support for
the TQM8548-BE modules. Furthermore disable USB, Wireless and IDE support
because it's not available on the STK85xx starter kit.

Signed-off-by: Wolfgang Grandegger <wg@grandegger.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>