powerpc/40x: Add support for the ESTeem 195E (PPC405EP) SBC

This patch adds support for the ESTeem 195E Hotfoot SBC.

There are several variants of the SBC deployed, single/dual
ethernet+serial, and also 4MB/8MB flash variations.  In the interest of
having a single kernel image boot on all boards, the cuboot shim detects
the differences and mangles the DTS tree appropriately.

With the exception of the CF interface that was never populated on
production boards, this code/DTS supports all boardpop options.

Signed-off-by: Solomon Peachy <solomon@linux-wlan.com>
Signed-off-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>