board/t1024qds: update pin multiplexing

board/t1024qds: update pin multiplexing

Add multiplexing support among SPI flash, TDM riser card and SDXC.
it routes SPI pins to SPI flash by default.
Route SPI pins to SD slot if "adaptor=sdxc" is set in hwconfig.
Route SPI pins to TDM riser card and do fixup for dts if "pin_mux=tdm"
is set in hwconfig.

Signed-off-by: Shengzhou Liu <Shengzhou.Liu@freescale.com>
Signed-off-by: Xie Xiaobo <X.Xie@freescale.com>
Signed-off-by: Zhao Qiang <B45475@freescale.com>
Reviewed-by: York Sun <yorksun@freescale.com>