dm: core: Add flags parameter to device_remove()

This patch adds the flags parameter to device_remove() and changes all
calls to this function to provide the default value of DM_REMOVE_NORMAL
for "normal" device removal.

This is in preparation for the driver specific pre-OS (e.g. DMA
cancelling) remove support.

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