eco32: add note about setting default devtree

Signed-off-by: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
eco32: add some missing uapi includes

Signed-off-by: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
eco32: implement switch_mm

Signed-off-by: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
eco32: implement flush_xxx routines

Signed-off-by: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>