linux-phytec-fsl

spi/mpc512x-psc: don't use obsolet cell-index property

Remove deprecated cell-index property and use spi alias to
obtain the SPI PSC number used for SPI bus id.

Signed-off-by: Anatolij Gustschin <agust@denx.de>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>