[POWERPC] Fix ucc_geth of_device discovery on mpc832x

mpc832x, as in mpc8360, needs to explicitly find and create the
platform device for ucc_geth in 2.6.19.  This code will likely be
readapted to Benh's new of_ methods for 2.6.20.

Signed-off-by: Kim Phillips <kim.phillips@freescale.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>