staging: greybus: uart: replace driver line-coding struct

staging: greybus: uart: replace driver line-coding struct

Drop the driver version of the line-coding request and use the protocol
definition directly as was originally intended instead.

This specifically avoids having the two versions of what is supposed to
be the same struct ever getting out of sync.

Note that this has in fact already happened once when the protocol
definition had its implicit padding removed while the driver struct
wasn't updated. The fact that we used the size of the then larger driver
struct when memcpying its content to the stack didn't exactly make
things better. A later addition of a flow-control field incidentally
made the structures match again.

Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20200514070548.4423-1-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>