qemu-ppce500: Update get_phys_ccsrbar_addr_early()

The logic of what fdt_get_base_address() will search for and return has
changed.  Rework get_phys_ccsrbar_addr_early() to perform the logic that
fdt_get_base_address used to perform.

Fixes: 336a4487 ("fdt: Correct fdt_get_base_address()")
Reviewed-by: Simon Glass <sjg@chromium.org>
Cc: Alexander Graf <agraf@suse.de>
Signed-off-by: Tom Rini <trini@konsulko.com>