arm: bootm: Add dm_remove_devices_flags() call to announce_and_cleanup()

This patch adds a call to dm_remove_devices_flags() to
announce_and_cleanup() so that drivers that have one of the removal flags
set (e.g. DM_FLAG_ACTIVE_DMA_REMOVE) in their driver struct, may do some
last-stage cleanup before the OS is started.

Signed-off-by: Stefan Roese <sr@denx.de>
Reviewed-by: Simon Glass <sjg@chromium.org>