This implements the vt100 show cursor command '[?25h' and the hide
cursor command '[?25l'. It is useful for displaying text on a non-active
(no stdout/stdin/stderr) console with 'echo'.
Signed-off-by: Bastian Stender <bst@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>