Staging: gdm724x: tty: Remove unnecessary macro 'gdm_tty_send'.

Remove the macro 'gdm_tty_send' which adds unnecessary complexity and has
arguments that could mistakenly be evaluated multiple times.

Signed-off-by: Quytelda Kahja <quytelda@tamalin.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>