powerpc/t4240qds: Add support to dump switch settings on t4240qds board

This function is called by "qixis_reset switch" command and
switch settings are calculated from qixis FPGA registers.

Signed-off-by: York Sun <yorksun@freescale.com>
Signed-off-by: Shaveta Leekha <shaveta@freescale.com>
Signed-off-by: Poonam Aggrwal <poonam.aggrwal@freescale.com>
Signed-off-by: Andy Fleming <afleming@freescale.com>