uboot-imx

mpc82xx: Remove SL8245 board and the now orpahned sk98lin network driver.

This code has compile problems and the company does not even exist any
more.  So we take the liberty to drop support for it.

Signed-off-by: Detlev Zundel <dzu@denx.de>
CC: Wolfgang Denk <wd@denx.de>
CC: Ben Warren <biggerbadderben@gmail.com>