rpi: Drop fdt_high and initrd_high

rpi: Drop fdt_high and initrd_high

These are not needed now since there is a bootm_size setting to keep
things within the lower part of memory.

Drop them.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Tom Rini <trini@konsulko.com>
Suggested-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Christopher Obbard <christopher.obbard@linaro.org>
Tested-by: Christopher Obbard <christopher.obbard@linaro.org> # CM4 1G
Reviewed-by: Christopher Obbard <christopher.obbard@linaro.org>
Tested-by: Christopher Obbard <christopher.obbard@linaro.org> # CM4 1G