linux/3.8: backport 'spi/of: Use DT aliases for assigning bus number' from 3.9

Signed-off-by: Gabor Juhos <juhosg@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt@36328 3c298f89-4303-0410-b956-a3cf2f4a3e73
mpc85xx: use static SPI bus number for TL-WDR4900

Signed-off-by: Gabor Juhos <juhosg@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt@36329 3c298f89-4303-0410-b956-a3cf2f4a3e73