dz: clean up and improve the setup of termios settings

A set of changes to the way termios settings are propagated to the serial
port hardware.  The DZ11 only supports a selection of fixed baud settings,
so some requests may not be fulfilled.  Keep the old setting in such a case
and failing that resort to 9600bps.  Also add a missing update of the
transmit timeout.  And remove the explicit encoding of the line selected
from writes to the Line Parameters Register as it has been preencoded by
the ->set_termios() call already.  Finally, remove a duplicate macro for
the Receiver Enable bit.

Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/serial/dz.h b/drivers/serial/dz.h
index 1e836c34..faf169e 100644
--- a/drivers/serial/dz.h
+++ b/drivers/serial/dz.h
@@ -109,8 +109,8 @@
 #define DZ_B7200         0x0D00
 #define DZ_B9600         0x0E00
 
-#define DZ_CREAD         0x1000               /* Enable receiver */
-#define DZ_RXENAB        0x1000               /* enable receive char */
+#define DZ_RXENAB        0x1000               /* Receiver Enable */
+
 /*
  * Addresses for the DZ registers
  */